IL277590B1

IL277590B1 - Composition for tin-silver alloy electroplating comprising a complexing agent

Info

Publication number: IL277590B1
Application number: IL277590A
Authority: IL
Original assignee: Basf Se
Priority date: 2018-03-29
Filing date: 2019-03-22
Publication date: 2023-12-01
Also published as: KR20200135481A; EP3775325A1; US20210025070A1; JP7383632B2; WO2019185468A1; IL277590A; CN111918985A; CN111918985B; IL277590B2; JP2021519388A; TW201942419A; TWI814800B

Description

WO 2019/185468 PCT/EP2019/057205 Composition for tin-silver alloy electroplating comprising a complexing agent Background of the Invention The invention relates to tin-silver alloy electroplating compositions comprising a complexing agent, their use and processes for tin-silver alloy electroplating.

Metals and metal-alloys are commercially important, particularly in the electronics industry where they are often used as electrical contacts, final finishes and solders.Leadfree solders, such as tin, tin-silver, tin-copper, tin-bismuth, tin-silver-copper, and others, are common metals used in solders. These solders are often deposited on semiconductor substrates by means of metal electroplating plating baths.

Certain applications for lead-free solder plating present challenges in the electronics industry. For example, when used as a capping layer on copper pillars, a relatively small amount of lead- free solder, such as tin or tin-silver solder, is deposited on top of a copper pillar.

A typical tin-silver plating solution comprises dissolved tin and silver ions, water, an acid electrolyte such as methane sulfonic acid in an amount sufficient to impart conductivity to the bath, an antioxidant, and proprietary additives to improve the uniformity of the plating and the quality of the metal deposit in terms of surface roughness and void formation. Such additives usually include complexing agents that are capable of forming a complex with silver in order to allow silver to be (a) stable in the solution in combination with tin, and (b) deposited in parallel to the less noble tin.

JP 2007218952 A, EP 166347 A, EP 144990 A disclose photographic films which comprise silver compounds and a sulfur containing compound comprising nitrogen containing ring system substituents like 1,8-Bis(2-pyridyl)-3,6-dithiaoctane or 1,11-Bis(2-pyridyl)-3,6,9-trithiaundecane.

JP 2006206946 A discloses silver plating bath comprising, among others, compounds of formula Ra-S-(CH2-CH2-S)n-Rb. The bath may be used for depositing silver on printed circuit boards, semiconductor integrated circuits, resistors, variable resistors, capacitors, filters, inductors, thermistors, crystal oscillators, switches, wire and other electronic components.

US 6607653 B1 discloses a composition for depositing a tin copper, a tin copper bismuth, or a tin copper silver alloy that comprises a specific sulfur containing compound. One of several dozens of compounds could be 1,10-di(2-pyridyl)-1 ,4,7,10-tetrathiadecane.

Surprisingly it was found that the compounds mentioned above may advantageously be used in electroplating baths to deposit tin-silver alloys.

It is an object of the present invention to provide a tin-silver electroplating composition that is stable over a long time without showing significant deterioration or aging, e.g. by strong coloring WO 2019/185468 PCT/EP2019/057205 or generating deposits and that is capable of electrodepositing tin-silver alloys on semiconductor substrates.

Summary of the Invention The present invention provides an aqueous composition comprising (a) metal ions comprising tin ions and silver ions and (b) at least one complexing agent of formula C1, C2 or C3 R1-X1-S-X21-[D1-X22-]nS-X3-R2 (C1) R1-X1-S-X31-D2-[X32-S-]nX3-R2 (C2) R3-X1־S-X41־[D3־X42־]nS-X3־R4 (C3) wherein X1, X3 are independently selected from a linear or branched C1-C12 alkanediyl, which may be unsubstituted or substituted by OH;X21, X22 are independently selected from(a) X1, which may be further substituted by -X5--COOR12, -X5-SO2-O-R12, a C2 to C6 polyoxyalkylene group of formula -(O-CH2-CHR11)Z-OH, ora combination thereof, and(b) -X1-NH-CO-X6-CO-NH-X1-;X31, X32 are independently selected from a chemical bond and X1;X41, X42 are independently selected from X1;X5 is a linear or branched C1 to C10 alkyl;X6 is selected from X1 and a divalent 5 or 6 membered aromatic group;R1, R2 are independently selected from a monovalent 5 or 6 membered aromatic N- heterocyclic group comprising one or two N atoms which are separated by at least one C atom, and its derivatives received by N-alkylation with a C1-C6- alkyl group, which may be substituted by -COOR12 or -SO2-O-R12, and which aromatic N- heterocyclic group may optionally further comprise, under the proviso that X21 is substituted by at least one OH, one S atom;R3, R4 are independently selected from a monovalent 5 or 6 membered aliphatic N- heterocyclic group comprising one N atom and one O atom;D1 is independently selected from S, O and NR10;D2 is (a) a divalent 5 or 6 membered aliphatic heterocyclic ring system comprising 1 or S atoms, or (b) a 5 or 6 membered aromatic heterocyclic ring system comprising at least two N atoms and optionally one or two S atoms;D3 is independently selected from S and NR10;n is an integer of from 0 to 5;z is an integer from 1 to 50; WO 2019/185468 PCT/EP2019/057205 R10 is selected from H and a linear or branched C1-C12 alkyl;R11 is selected from H and a linear or branched C1 to C6 alkyl; andR12 is selected from R10 and a cation.

With the aid of the complexing agents the plating baths are stable over a long time without showing coloring or deposits and are capable of electrodepositing tin-silver alloys on semiconductor substrates, particularly tin-silver alloy solder bumps.

The invention further relates to the use of a tin-silver alloy plating bath comprising a composition as defined herein for depositing tin-silver alloys on a substrate comprising features having an aperture size of 500 nm to 500 pm.

The invention further relates to a process for depositing a tin-silver alloy layer on a substrate by a) contacting a composition as defined herein with the substrate, andb) applying a current to the substrate for a time sufficient to deposit a tin or tin alloy layer onto the substrate,wherein the substrate comprises features having an aperture size of 500 nm to 500 pm and the deposition is performed to fill these features.

The Invention further relates to a compound of formula C1, C2 or C3 R1-X1-S-X21-[D1-X22-]nS-X3-R2 (C1) R1-X1-S-X31-D2-[X32-S-]nX3-R2 (C2)R3-X1-S-X41-[D3-X42-]nS-X3-R4 (C3) wherein X1, X3 are independently selected from a linear or branched C1-C12 alkanediyl, which may be unsubstituted or substituted by OH;X21, X22 are independently selected from(a) X1, which may be further substituted by -X5-COOR12, -X5-SO2-O-R12, a C2 to Cpolyoxyalkylene group of formula -(O-CH2-CHR11)Z-OH, ora combination thereof, and(b) -X1-NH-CO-X6-CO-NH-X1-;X31, X32 are independently selected from a chemical bond and X1;X41, X42 are independently selected from X1;X5 is a linear or branched C1 to C10 alkyl;X6 is selected from X1 and a divalent 5 or 6 membered aromatic group;R1, R2 are independently selected from a monovalent 5 or 6 membered aromatic N- heterocyclic group comprising one N atom or two N atoms which are separated by at WO 2019/185468 PCT/EP2019/057205 least one C atom, and its derivatives received by N-alkylation with a C1-C6- alkyl group, which may be substituted by --COOR12 or-SO2-O-R 12, and which aromatic N- heterocyclic group may optionally further comprise, under the proviso that X21 is substituted by at least one OH, one S atom;R3, R4 are independently selected from a monovalent 5 or 6 membered aliphatic N- heterocyclic group comprising one N atom and one O atom;D1 is independently selected from S, O and NR10;D2 is (a) a divalent 5 or 6 membered aliphatic heterocyclic ring system comprising 1 or S atoms, or (b) a 5 or 6 membered aromatic heterocyclic ring system comprising at least two N atoms and optionally one or two S atoms;D3 is independently selected from S and NR10;n is an integer of from 0 to 5;z is an integer from 1 to 50;R10 is selected from H and a linear or branched C1-C12 alkyl; andR11 is selected from H and a linear or branched C1 to C6 alkyl; andR12 is selected from R10 and a cation. excluding 1,8-Bis(2-pyridyl)-3,6-dithiaoctane; 1,9-Bis-(2-pyridyl)-2,5,8-trithianonane; 1,11 -Bis(2- pyridyl)-3,6,9-trithiaundecane; 1,6-Bis-(2-pyridyl)-2,5-dithiahexane; 1,13-Bis(2-pyridyl)-2,5,9,12- tetrathiatridecane; 1,9-Bis(2-pyridyl)- 5-oxa-2,8-dithianonane; 1,8-Bis(4-pyridyl)-3,6- dithiaoctane; 1 -[2-[2-(2-imidazol-1 -ylethylsulfanyl)ethylsulfanyl]ethyl]imidazole; 1 -[2-[2-[2-(2- imidazol-1-ylethylsulfanyl)ethylsulfanyl]ethylsulfanyl]ethyl]imidazole; 1,9-Bis(2-pyridyl)-3,7- dithianonane; 1,10-Bis(2-pyridyl)-3,8-dithiadecane.

Detailed Description of the Invention Complexing agents according to the invention It was found that compositions for tin-silver alloy electroplating according to the invention comprising at least one complexing agent as described below are stable over a long time without showing coloring or deposits and are capable of electrodepositing tin-silver alloys on semiconductor substrates, particularly tin-silver alloy solder bumps. Long time stability here means a stable bath over a period of at least 6 months.

Besides tin ions and silver ions the aqueous compositions, preferably solutions, according to the present invention comprises at least one compound of formula C1, C2 and C3, as further described below.

First embodiment The aqueous composition may comprise a complexing agent compound of formula C1: WO 2019/185468 PCT/EP2019/057205 R1-X1-S-X21-[D1-X22-]nS-X3-R2 (01) wherein X1, X3 are independently selected from a linear or branched C1-C12 alkanediyl, which may be unsubstituted or substituted by OH;X21, X22 are independently selected from(a) X1, which may be further substituted by -X5--COOR12, -X5-SO2-O-R12, a C2 to C6 polyoxyalkylene group of formula -(O-CH2-CHR11)Z-OH, ora combination thereof, and(b) -X1-NH-CO-X6-CO-NH-X1-;X5 is a linear or branched C1 to C10 alkyl;X6 is selected from X1 and a divalent 5 or 6 membered aromatic group;R1, R2 are independently selected from a monovalent 5 or 6 membered aromatic N- heterocyclic group comprising one or two N atoms which are separated by at least one C atom, and its derivatives received by N-alkylation with a 01-06- alkyl group, which may be substituted by --COOR12 or -SO2-O-R12, and which aromatic N- heterocyclic group may optionally, under the proviso that X21 is substituted by at least one OH, further comprise one S atom;D1 is independently selected from S, O and NR10;n is an integer of from 0 to 5;z is an integer from 1 to 50;R10 is selected from H and a linear or branched 01-012 alkyl; andR11 is selected from H and a linear or branched C1 to C6 alkyl; and R12 is selected from R10 and a cation.

Essentially, such complexing agents comprise at least two sulfur atoms which are separated by at least a spacer group X21 and which are terminated by 5 or 6 membered aromatic N- heterocyclic group comprising one or two N atoms, again separated by spacer groups X1 and X3.

Preferred spacer groups X1 and X3 may be linear or branched 01-08 alkanediyl, more preferred 01-06 alkanediyl, most preferably selected from methanediyl, ethanediyl, propanediyl, and butanediyl. Such alkanediyl may either be unsubstituted or substituted by hydroxy (OH) functional groups.

In a first alternative, preferred spacer groups X21 and X22 may be linear or branched 01-alkanediyl, more preferred 01-06 alkanediyl, most preferably 01-04 alkanediyl. Such alkanediyl may either be unsubstituted or substituted by hydroxy (OH) functional groups. In contrast to spacer groups X1 and X3, spacer groups X21 and, if applicable, X22 may be further substituted by -X5--COOR12 ׳ or-X 5-SO2-O-R12, wherein X5 is a linear or branched C1 to C10 alkyl, preferably a C1 to C8 alkyl, more preferably a C1 to C6 alkyl, most preferably a 02 to 06 alkyl.

WO 2019/185468 PCT/EP2019/057205 Linear alkyl and alkyl with short C1 or C2 branches are preferred, spacer groups X21 and, if applicable, X22 may also be further substituted by one or more C2 to C6 polyoxyalkylene group of formula -(O-CH2-CHR11)Z-OH, wherein R11 is selected from H and a linear or branched C1 to Calkyl, preferably H, ethyl, or propyl , most preferably H or methyl, z is an integer from 1 to 50, preferably from 1 to 30, even more preferably from 1 to 20, most preferably from 1 to 10. For more details, it is referred to the description of the polyoxyalkylene group in Rs11 of formula Sbelow. Generally, if R12 is H, groups -COOR12, and -X5-SO2-O-R12 may be deprotonated and Rwould be cation. Useful cations are any cations that do not interfere with the complexing or electroplating, preferably metal cations or NR104+, most preferably Na +, K+, or tetramethyl ammonium.

In a second alternative, preferred spacer groups X21 and X22 may be -X1-NH-CO-X6-CO-NH-X1-, wherein X6 is selected from X1 and a divalent 5 or 6 membered aromatic group. Preferred aliphatic groups X21 and X22 are methanediyl, ethanediyl, propanediyl or butanediyl. Preferred aromatic groups X21 and X22 are phenyl, imidazole, thiazole, and pyridine, most preferably phenyl.

In formula C1 n may be 0 or an integer from 1 to 5. If n is 0, the complexing agent comprises only two sulfur atoms. If n is greater than 0, one or more further heteroatoms D1 are present. Preferably n is 0 or an integer from 1 to 4, more preferably 0 or an integer from 1 to 3, even mose preferably 0, 1 or 2, most preferably 0 or 1.

The heteroatomsZ-groups D1 may be S, O and NR10, preferably S or O. Herein, R10 is selected from H and a linear or branched C1 to C12 alkyl, preferably from H and a linear or branched C1 to C6 alkyl, most preferably from H, methyl, ethyl, propyl and butyl.

The termination groups R1 and R2 may be selected from a monovalent 5 or 6 membered aromatic N-heterocyclic group comprising one or two N atoms. The N atoms are separated by at least one C atom. Examples of 5 membered N-heterocyclic group are, without limitation, N- imidazole, N-pyrazoL Examples of 6 membered N-heterocyclic group are, without limitation, 2- pyridine, 3-pyridine, 4-pyridine, and 2-pyrazine.

Furthermore, the cationic derivatives received by N-alkylation with a C1-C6- alkyl group, preferably alkylation with methyl, ethyl, propyl or butyl may be used in the plating bath according to the invention. Examples of such cationic N-heterocyclic group are, without limitation, N-alkyl- pyridinium cations. Any suitable anion, such as but not limited to sulfate and methane sulfonate may be used in combination with the cations.

In an alternative within the first embodiment the aromatic N-heterocyclic group further comprises, one S atom. However, in this embodiment it is required that the spacer group X(including all spacer groups X21 and X22 partly incorporating X1) is substituted by at least one OH functional group. Examples of 5 membered N-heterocyclic groups comprising sulfur are 2- WO 2019/185468 PCT/EP2019/057205 thiazole, thiadiazol, and isothiazoL Without limitation, particularly preferred compounds according to the first embodiment are: R1, R2 D1 X1 X3 X21,X22 n N-lmidazole Et Et E 0N-lmidazole S Me Me Et 1N-lmidazole S Et Et Et 1N-lmidazole Me Me Et 0N-lmidazole s Me Me Et 2N-lmidazole s Et Et Et 2N-lmidazole Et Et cis-Bu(OH)2 0N-lmidazole Et Et trans-Bu(OH)2 0N-lmidazole Me Me cis-Bu(OH)2 0N-lmidazole Me Me trans-Bu(OH)2 0N-lmidazole 0 Me Me Et 1N-lmidazole 0 Et Et Et 1N-lmidazole 0 Et Et Et 2N-lmidazole 0 Et Et Et, Pr(Et)(MeOH) 2N-lmidazole Et Et Pr-OH 0N-lmidazole Et Et iPr(OH) 0N-lmidazole Et Et Pr(BuCOOH) 0N-lmidazole Et Et Et 0N-lmidazole s Pr Pr Et 1N-lmidazole Pr Pr Bu(OH)2 0N-lmidazole Et Et Bu(OH)2 0N-lmidazole Et Et Pr 0N-lmidazole Et Et Pe 0N-lmidazole 0 Pr Pr Pr, Pr-OH, Pr 2N-lmidazole Et Et Et-S03H or Et-SO3Na 0N-lmidazole Et Et Bu[(EO)5]2 0N-lmidazole Et Et Bu[(EO)30]2 0N-lmidazole Et Et Bu[(EO)5(PO)5]2 0N-lmidazole Et Et -Et-NH-CO-Ph-CO-NH-Et- 02-Pyrazine Et Et Et 02-Pyrazine s Me Me Et 12-Pyrazine s Et Et Et 12-Pyrazine Me Me Et 02-Pyrazine s Me Me Et 22-Pyrazine s Et Et Et 22-Pyrazine Et Et cis-Bu(OH)2 0 WO 2019/185468 PCT/EP2019/057205 2-Pyrazine Et Et trans-Bu(0H)2 02-Pyrazine Me Me cis-Bu(0H)2 02-Pyrazine Me Me trans-Bu(0H)2 02-Pyrazine 0 Me Me Et 12-Pyrazine 0 Et Et Et 12-Pyrazine 0 Et Et Et 22-Pyrazine 0 Et Et Et, Pr(Et)(MeOH) 22-Pyrazine Et Et Pr-OH 02-Pyrazine Et Et Bu(OH)2 02-Pyrazine Et Et iPr(OH) 02-Pyrazine Et Et Pr(BuCOOH) 02-Pyrazine Me Me Pr 02-Pyrazine Me Me Pe 02-Pyrazine Et Et Pr 02-Pyrazine Et Et Pe 02-Pyrazine 0 Pr Pr Pr, Pr-OH, Pr 22-Pyrazine Et Et Et-SO3H or Et-SO3Na 02-Pyrazine Et Et Bu[(EO)5]2 02-Pyrazine Et Et Bu[(EO)30]2 02-Pyrazine Et Et Bu[(EO)5(PO)5]2 02-Pyrazine Et Et -Et-NH-CO-Ph-CO-NH-Et- 02-Thiazole Et Et Et 02-Thiazole s Me Me Et 12-Thiazole s Et Et Et 12-Thiazole Me Me Et 02-Thiazole s Me Me Et, Pr 22-Thiazole s Et Et Et, Pr 22-Thiazole Et Et cis-Bu(OH)2 02-Thiazole Et Et trans-Bu(OH)2 02-Thiazole Me Me cis-Bu(OH)2 02-Thiazole Me Me trans-Bu(OH)2 02-Thiazole 0 Me Me Et 12-Thiazole 0 Et Et Et 12-Thiazole 0 Et Et Et 22-Thiazole 0 Et Et Et, Pr(Et)(MeOH) 22-Thiazole Et Et Pr-OH 02-Thiazole Et Et iPr(OH) 12-Thiazole Et Et Pr(BuCOOH) 12-Thiazole i-Pr i-Pr trans-Bu(OH)2 02-Thiazole i-Pr i-Pr cis-Bu(OH)2 02-Thiazole Et Et Pr 0 WO 2019/185468 PCT/EP2019/057205 2-Thiazole Et Et Pe 02-Pyridine Et Et Et 02-Pyridine S Me Me Et 12-Pyridine S Et Et Et 12-Pyridine Me Me Et 02-Pyridine S Me Me Et, Pr 22-Pyridine S Et Et Et, Pr 22-Pyridine Et Et cis-Bu(0H)2 02-Pyridine Et Et trans-Bu(0H)2 02-Pyridine Me Me cis-Bu(0H)2 02-Pyridine Me Me trans-Bu(0H)2 02-Pyridine 0 Me Me Et 12-Pyridine 0 Et Et Et 12-Pyridine 0 Et Et Et 22-Pyridine 0 Et Et Et, Pr(Et)(MeOH) 22-Pyridine Et Et Pr-OH 02-Pyridine Et Et Bu 02-Pyridine Et Et Pe 02-Pyridine Et Et iPr(OH) 02-Pyridine Et Et Pr(BuCOOH) 02-Pyridine Et Et Pr 02-Pyridine 0 Pr Pr Pr, Pr-OH, Pr 22-Pyridine Et Et Et-SO3H or Et-SO3Na 02-Pyridine Et Et Bu[(EO)5]2 02-Pyridine Et Et Bu[(EO)30]2 02-Pyridine Et Et Bu[(EO)5(PO)5]2 02-Pyridine Et Et -Et-NH-CO-Ph-CO-NH-Et- 03-Pyridine Et Et trans-Bu(OH)2 03-Pyridine Et Et cis-Bu(OH)2 03-Pyridine Me Me cis-Bu(OH)2 03-Pyridine Me Me trans-Bu(OH)2 03-Pyridine Et Et Et 03-Pyridine 0 Et Et Et 13-Pyridine 0 Et Et Et 23-Pyridine S Et Et Et 13-Pyridine S Et Et Et, Pr 23-Pyridine Et Et Bu 03-Pyridine Et Et Pe 03-Pyridine s Me Me Et 13-Pyridine s Me Et Et 23-Pyridine 0 Me Me Et 1 WO 2019/185468 PCT/EP2019/057205 Abbreviations: Me=Methyl/Methanediyl, Et= Ethyl/Ethanediyl; Pr=Propyl/Propanediyl; Bu=Butyl/Butanediyl; Pe=Pentyl/Pentanediyl; Bu(OH)2=2,3-dihydroxy butanediyl, i- Pr=lsopropanediyl, Pr(Et)(MeOH)=2-ethyl,2-hydroxyethyl propanediyl, Pr(BuCOOH)=2- carboxybutyl propanediyl, Ph=phenyl, EO=oxyethylene, PO=oxypropylene, 2-038-Me-N- Pyridinium=2-pyridine quaternized with methyl that comprises a sulfonic acid substituent. 3- Pyridine 0 Me Me Et 23- Pyridine Et Et Pr 04-Pyridine Et Et trans-Bu(OH)2 04-Pyridine Et Et cis-Bu(OH)2 04-Pyridine Me Me cis-Bu(OH)2 04-Pyridine Me Me trans-Bu(OH)2 04-Pyridine Et Et Et 04-Pyridine 0 Et Et Et 14-Pyridine 0 Et Et Et 24-Pyridine s Et Et Et 14-Pyridine s Et Et Et, Pr 24-Pyridine Et Et Bu 04-Pyridine Et Et Pe 04-Pyridine s Me Me Et 14-Pyridine s Me Et Et 24-Pyridine 0 Me Me Et 14- Pyridine 0 Me Me Et 24- Pyridine Et Et Pr 02-Me-N-PyridiniunT ־ Et Et Et 02-O3S-Me-N-Pyridinium Me Me Et 02-O3S-Et-N-Pyridinium Et Et Et 02-O3S-Pr-N-Pyridinium Et Et Et 02-O3S-Pr-N-Pyridinium Et Et trans-Bu(OH)2 02-O3S-Pr-N-Pyridinium Et Et cis-Bu(OH)2 0 Second embodiment The aqueous composition may comprise a complexing agent compound of formula C2: R1-X1-S-X31-D2-[X32-S-]nX3-R2 (C2) wherein X1,X3 X31, X32R1, R2 are independently selected from a linear or branched C1-C12 alkanediyl, which may be unsubstituted or substituted by OH;are independently selected from a chemical bond and X1;are independently selected from a monovalent 5 or 6 membered aromatic N- WO 2019/185468 PCT/EP2019/057205 heterocyclic group comprising one or two N atoms which are separated by at least one C atom, and its derivatives received by N-alkylation with a C1-C6- alkyl group, which aromatic N-heterocyclic group may optionally further comprise one S atom;D2 is (a) a divalent 6 membered aliphatic heterocyclic ring system comprising 1 or 2 S atoms, or (b) a 5 or 6 membered aromatic heterocyclic ring system comprising at least two N atoms and optionally one or two S atoms;n is an integer of from 0 to 5;R10 is selected from H and a linear or branched C1-C12 alkyl.

Again, such complexing agents comprise at least two sulfur atoms which are separated by a spacer group X31 and which are terminated by 5 or 6 membered aromatic N-heterocyclic group comprising one or two N atoms, again separated by spacer groups X1 and X3. In contrast to the first embodiment, the second (or third) sulfur atom is incorporated in either a divalent membered aliphatic heterocyclic ring system comprising 1 or 2 S atoms, or a 5 or 6 membered aromatic heterocyclic ring system comprising at least two N atoms and optionally one or two S atoms.

Preferred spacer groups X1 and X3 may be linear or branched C1-C8 alkanediyl, more preferred C1-C6 alkanediyl, most preferably selected from methanediyl, ethanediyl, propanediyl, and butanediyl. Such alkanediyl may either be unsubstituted or substituted by hydroxy (OH) functional groups.

Preferred spacer groups X31 and X32 may be linear or branched C1-C8 alkanediyl, more preferred C1-C6 alkanediyl, most preferably C1-C4 alkanediyl. Alternatively, and also preferred, X31 and X32 may be a chemical bond. Such alkanediyl may either be unsubstituted or substituted by hydroxy (OH) functional groups. Linear alkyl is preferred. n may be 0 or an integer from 1 to 5. If n is 0, the complexing agent comprises only one sulfur atom in the main chain and optionally one or more sulfur atoms in the ring system D2. If n is greater than 0, one or more further sulfur atoms are present in the main chain. Preferably n is or an integer from 1 to 4, more preferably 0 or an integer from 1 to 3, most preferably 0, 1 or 2.

In one alternative, the ring system D2 may be a divalent 5 or 6 membered aliphatic heterocyclic ring system comprising 1 or 2 S atoms. Such aliphatic heterocyclic systems may further comprise O atoms or N-R10 groups. Preferably, the 5-membered aliphatic heterocyclic ring systems have 2 S atoms or 1 S and one N atom. More preferably D2 is selected from Dithiolane and Thiazolidine. Preferably, the 6-membered aliphatic heterocyclic ring system have 2 S atoms or 1 S and one N atom. Most preferred ring systems D2 are dithiane, particularly 2,5 dithiane, and thiomorpholine.

In another alternative, the ring system D2 may also be a 5 or 6 membered aromatic heterocyclic ring system comprising at least two N atoms and optionally one or two S atoms. Such aromatic WO 2019/185468 PCT/EP2019/057205 heterocyclic systems may further comprise an O atom or a carbonyl group. Most preferred ring systems D2 are Amino-1,3,5-Triazin and 1,3,4-thiadiazole-2-thione.

Like the first embodiment, the termination groups R1 and R2 may be selected from a monovalent or 6 membered aromatic N-heterocyclic group comprising one or two N atoms. Examples of membered N-heterocyclic group are, without limitation, N-imidazole, N-pyrazol, and 2-thiazole. Preferred are N-imidazole and N-pyrazol. Examples of 6 membered N-heterocyclic group are, without limitation, 2-pyridine, 3-pyridine, 4-pyridine, and 2-pyrazine. Preferred are 2-pyridine, 4- pyridine, and 2-pyrazine.

In an alternative within the third embodiment the aromatic N-heterocyclic group further comprises, one S atom. Examples of 5 membered N-heterocyclic group comprising sulfur are 2- Thiazole, Thiadiazol, and IsothiazoL Like the first embodiment, the cationic derivatives received by N-alkylation with a C1-C6- alkyl group, preferably alkylation with methyl, ethyl, propyl or butyl may be used in the plating bath according to the invention. Examples of such cationic N-heterocyclic group are, without limitation, N-methyl-pyridinium cations. Any suitable anion, such as but not limited to sulfate and methane sulfonate may be used in combination.

Particularly preferred compounds according to the second embodiment are: R1, R2 D2 X1 X3 X31,X32 n N-lmidazole 1,3,4-thiadiazole-2-thione Et Et bond 0N-lmidazole 2,5 dithiane Et Et Me 1N-lmidazole 2,5 dithiane Me Me Me 1N-lmidazole 2,5 dithiane Pr Pr Me 1N-lmidazole 2,5 dithiane Et Et Et 1N-lmidazole Amino-1,3,5-T riazine Et Et bond 1N-lmidazole Amino-1,3,5-T riazine Me Me bond 1N-lmidazole 1,3,5-Triazine Et Et bond 12-Pyrazine 1,3,4-thiadiazole-2-thione Et Et bond 02-Pyrazine 2,5 dithiane Et Et Me 12-Pyrazine Amino-1,3,5-T riazine Et Et bond 12-Pyrazine Amino-1,3,5-T riazine Me Me bond 12-Pyrazine 1,3,5-Triazine Et Et bond 12-Thiazole 1,3,4-thiadiazole-2-thione Et Et bond 02-Thiazole 2,5 dithiane Et Et Me 12-Thiazole Amino-1,3,5-T riazine Et Et bond 12-Thiazole Amino-1,3,5-T riazine Me Me bond 12-Thiazole 1,3,5-Triazine Et Et bond 12-Pyridine 1,3,4-thiadiazole-2-thione Et Et bond 0 WO 2019/185468 PCT/EP2019/057205 Abbreviations: Me=Methyl/Methanediyl, Et= Ethyl/Ethanediyl; Bu(OH)2=2,3-dihydroxy 2-Pyridine 2,5 dithiane Et Et Me 12-Pyridine Amino- 1,3,5-T riazine Et Et bond 12-Pyridine Amino- 1,3,5-T riazine Me Me bond 12-Pyridine 1,3,5-Triazine Et Et bond 13-Pyridine 1,3,4-thiadiazole-2-thione Et Et bond 03-Pyridine 2,5 dithiane Et Et Me 13-Pyridine Amino- 1,3,5-T riazine Et Et bond 13-Pyridine Amino- 1,3,5-T riazine Me Me bond 13-Pyridine 1,3,5-Triazine Et Et bond 14-Pyridine 1,3,4-thiadiazole-2-thione Et Et bond 04-Pyridine 2,5 dithiane Et Et Me 14-Pyridine Amino- 1,3,5-T riazine Et Et bond 14-Pyridine Amino- 1,3,5-T riazine Me Me bond 14-Pyridine 1,3,5-Triazin Et Et bond 1 butanediyl, Pr=Propyl/Propanediyl Third embodiment The aqueous composition may comprise a complexing agent compound of formula C3: R3-X1-S-X41-[D3-X42-]nS-X3-R4 (C3) wherein X1, X3 are independently selected from a linear or branched C1-C12 alkanediyl, which may be unsubstituted or substituted by OH;X41, X42 are independently selected from X1;R3, R4 are independently selected from a monovalent 5 or 6 membered aliphatic N-heterocyclic group comprising one N atom and one O atom;D3 is selected from S and NR10;n is an integer of from 0 to 5;R10 is selected from H and a linear or branched C1-C12 alkyl.

Like the first embodiment, such complexing agents comprise at least two sulfur atoms which are separated by at least a spacer group X41 and optionally X42, and which are terminated by 5 or membered aliphatic N-heterocyclic group comprising one N and one O atom, again separated by spacer groups X1 and X3.

Preferred spacer groups X1 and X3 may be linear or branched C1-C8 alkanediyl, more preferred C1-C6 alkanediyl, most preferably C1-C4 alkanediyl. Such alkanediyl may either be unsubstituted or substituted by hydroxy (OH) functional groups.

WO 2019/185468 PCT/EP2019/057205 Preferred spacer groups X41 and X42 may be linear or branched C1-C8 alkanediyl, more preferably C1-C6 alkanediyl, most preferably C1-C4 alkanediyl. Such alkanediyl may either be unsubstituted or substituted by hydroxy (OH) functional groups. Linear alkyl is preferred. n may be 0 or an integer from 1 to 5. If n is 0, the complexing agent comprises only two sulfur atoms. If n is greater than 0, one or more further heteroatoms D1 are present. Preferably n is or an integer from 1 to 4, more preferably 0 or an integer from 1 to 3, most preferably 0, 1 or 2.

The heteroatomsZ-groups D3 may be selected from S and NR10, preferably S. Herein, R10 is selected from H and a linear or branched C1 to C12 alkyl, preferably from H and a linear or branched C1 to C6 alkyl, most preferably from H, methyl, ethyl, propyl and butyl.

The termination groups R3 and R4 may be selected from a monovalent 5 or 6 membered aliphatic N-heterocyclic group comprising one N atom and one O atom incorporated in the ring system or attached to the ring system, such as but not limited to C=O groups. Examples of membered heterocyclic group are, without limitation, N-pyrrolidone, N-oxazolidine, succinimide, and N-hydroxy succinimide. Preferred is N-pyrrolidone. An examples of a 6 membered heterocyclic group is, without limitation, N-morpholine.

Particularly preferred complexing agents are: R1, R2 D3 X1 X3 X41,X42 n N-Morpholine Et Et Bu(OH)2 0N-Morpholine Et Et Et 0N-Morpholine Me Me Me 0N-Morpholine Me Me Bu(OH)2 0N-Morpholine S Et Et Bu(OH)2 1N-Morpholine S Et Et Et 1N-Morpholine s Me Me Me 1N-Morpholine s Me Me Bu(OH)2 1N-Pyrrolidone Et Et Bu(OH)2 0N-Pyrrolidone Et Et Et 0N-Pyrrolidone Me Me Me 0N-Pyrrolidone Me Me Bu(OH)2 0N-Pyrrolidone s Et Et Bu(OH)2 1N-Pyrrolidone s Et Et Et 1N-Pyrrolidone s Me Me Me 1N-Pyrrolidone s Me Me Bu(OH)2 1Abbreviations: Me=Methyl/Methanediyl, Et= Ethyl/Ethanediyl; Bu(OH)2=2,3-hydroxy butanediyl Particular complexing agents are those selected from: 40 The tin or tin alloy electroplating bath may further contain additional complexing agents for complexing tin and/or any other metal present in the composition. A typical other complexing agent is 3,6-Dithia-1,8-octanedioL GO cnGO olD cn lD o cn cn lD O 0) סג CD O) CD O O) CD lD lD 0) O) 0) 0) 0) 0) o lD O) O) O) O) 0) 0) o lD O) 0) CD CD II CD 0) 0) 0) O) O) 0) 0) lD O) 0) Cn 0) o lD O) CD O) CD cn CD CD CD 0) cn 0) CD 0) CD 0) 0) o 0) o lD lD 0) 0) CD O) O) 0) CD CD O O CD lD CD O 0) 0) CD אנ o CD O CD O אנ CD CD CD 0) 0) אנ CD אנאנפאנ אנאנ אנ סנאנסג סגסס O) CD CD cn CD ג 0 CD 0) O) 0) cn 0) o 0) אנסג סג CD O) O) CD O) o 0) cn 0) 0) 0) 0) 0) 0) CD 0) O) 0) 0) אנ סנ סנ סגס U1 ס CD סנ סנאנ CD אנסנ סנ CD CD סנסנאנסנ ססנסאנ סנאנ CD CD O סנ סנ CD סנ CD אנסנ CD אנסנספ CD O סנ CD סנסנ CD סנ CD cn סנ סנ ס CD אנ סנסנסנסנסנססנ CD cn סנסנאנ סנ CD סנסנ CD CD CD אנ ססנ CD O אנאנסנפסנ סנסנאנ סנסנ אנ סנספס CD ׳V1 אנסנ אנcn ס CD סנ CD ׳V1 אנ סנ סנ CD אנס סאנ סנאנ ס דכ ס אניאנאנאנcnאנ אנאנ cnאנ אנ יאנאנאנ ס דכ ס אנ יאנאנ אנאנ אנ cn אנ cn אנ יאנאנאנ CD CD סנסנ CD N CD CD CD אנ סנ N סנסנ N אנxס אנxס אנ cn אנ cn 00 'VI ס דכ סנ CD ס כ ש CD אנאנcnאנ CD ש ס כ ש CD ס דכ ש CD אנ ס כ שס ס דכ ש CD ס דכ ש CD ס כ ש CD ס כ שס ש CD אנ ס דכ ש שסס כ CD אנ ש CD אנ ש CD אנ ס כ CD ש CD אנ אנ כ CD אנ אנ ש CD אנ ס CD ש CD אנ cnxש אנ שס כ ש CD ש CD CD ס ש CD CD ז - ש CD ס ש CD שס כ ש CD CD ז - ש ש CD ש CD אנ CD O ש CD CD ז - שש דכ CD ש CL CD ס ש CD ס X ש CD ס ש CD ס X ש ש 0 ז - ש CL CD ס ש CD CD ס ש CD ס X ש ש 0 ז - ש CL CD ס ש CD CD ס cdxש ש CD אנ ש CD אנ ש CD אנ CD ז - שש דכ CD ש CL CD ס ש CD ש צב CD שס כ ש CD CD ש CD ש CD CD CD1 ש O) ש cn סג אנאנ סנאנש N ס_ אנ סג אנ סנ אנ ש N ס_ CD אנ סנ אנ סנ אנ סנאנ סג אנש N ס ש N ס ש N ס ש N ס CD סנ אנ סג אנ סג אנ סג אנ סג ש CD סג CD CD אנcn אנcn אנcn אנcn ססג CD ש סגס כ CD O CD ש סגס כ CD סכסג" אנ סכסג" סג סכסג" סכסג"סג cnסכסג" סכסג" סכסג" סכסג"אנ סכסג" סכסג"אנ cnסכסג" אנ סכסג" CD Oס פ ס סג אנפ סO פ CD פ CD פ CD פ CD פ CD פ פ CD O פ ס פ ש CD פ CD ס X ש פ אנ ש פ ס CD סגOס סגOס פאנ פאנ פאנ סג אנ פ ס פ CD פ CD CD סכ סג" אנ פ CD CD סכ סג" אנ פ CD פ CD סגס WO 2019/185468 PCT/EP2019/057205 Other typical complexing agents are polyoxy monocarboxylic acids, polycarboxylic acids, aminocarboxylic acids, lactone compounds, and salts therof.

Other complexing agents are organic thiocompounds like thiourea, thiols or thioethers as disclosed in US 7628903, JP 4296358 B2, EP 0854206 A and US 8980077 B2.

It is preferred that the tin alloy bath comprises no other complexing agents except those according to the invention.

A large variety of additives may typically be used in the bath to provide desired surface finishes for the plated tin alloy bump. Usually more than one additive is used with each additive forming a desired function. Advantageously, the electroplating baths may contain one or more of suppressing agents (also often referred to as surfactants), grain refiners, complexing agents in case of alloy deposition, antioxidants, and mixtures thereof. Most preferably the electroplating bath comprises a leveler and optionally a grain refiner in addition to the suppressing agent according to the present invention. Other additives may also be suitably used in the present electroplating baths.

Suppressing agents or surfactants One or more suppressing agents (also referred to as surfactants) may be present in the tin- silver alloy plating bath.

Any nonionic surfactant may be used in the present compositions. Typically, the nonionic surfactants have an average molecular weight from 200 to 100,000, preferably from 500 to 50,000, more preferably from 500 to 25,000, and yet more preferably from 750 to 15,000. Such nonionic surfactants are typically present in the electrolyte compositions in a concentration from to 10,000 ppm, based on the weight of the composition, and preferably from 5 to 10,000 ppm. Preferred alkylene oxide compounds include polyalkylene glycols, such as but not limited to alkylene oxide addition products of an organic compound having at least one hydroxy group and carbon atoms or less and tetrafunctional polyethers derived from the addition of different alkylene oxides to low molecular weight polyamine compounds.

Preferred polyalkylene glycols are polyethylene glycol and polypropylene glycol. Such polyalkylene glycols are generally commercially available from a variety of sources and may be used without further purification. Capped polyalkylene glycols where one or more of the terminal hydrogens are replaced with a hydrocarbyl group may also be suitably used. Examples of suitable polyalkylene glycols are those of the formula R-O-(CXYCX'Y'O)nR' where R and R' are independently chosen from H, C2 - C20 alkyl group and C6-C20 aryl group; each of X, Y, X' and Y' is independently selected from hydrogen, alkyl such as methyl, ethyl or propyl, aryl such as WO 2019/185468 PCT/EP2019/057205 17 phenyl, or aralkyl such as benzyl; and n is an integer from 5 to 100,000. Typically, one or more of X, Y, X' and Y' is hydrogen.

Suitable EO/PO copolymers generally have a weight ratio of EO:PO of from 10:90 to 90:10, and preferably from 10:90 to 80:20. Such EO/PO copolymers preferably have an average molecular weight of from 750 to 15,000. Such EO/PO copolymers are available from a variety of sources, such as those available from BASF under the tradename "PLURONIC".

Suitable alkylene oxide condensation products of an organic compound having at least one hydroxy group and 20 carbon atoms or less include those having an aliphatic hydrocarbon from one to seven carbon atoms, an unsubstituted aromatic compound or an alkylated aromatic compound having six carbons or less in the alkyl moiety, such as those disclosed in US 5,174,887. The aliphatic alcohols may be saturated or unsaturated. Suitable aromatic compounds are those having up to two aromatic rings. The aromatic alcohols have up to carbon atoms prior to derivatization with ethylene oxide. Such aliphatic and aromatic alcohols may be further substituted, such as with sulfate or sulfonate groups.

Preferred surfactants are those of formula S1: RS13 RS15 RS14 L J S The compounds of formula S1 may be prepared by reacting a polyamine starter with one or more C2 to C6 alkylene oxides to form the respective amine-based suppressing agents.

Generally, s may be an integer of from 1 to 6. Preferably s is an integer from 1 to 4, most preferably s is 1 or 2.

Xs1 and Xs2 are a divalent spacer group within the polyamine starter. They may independently be selected from a linear or branched C1-C12 alkanediyl. Such alkanediyl spacer are unsubstituted but may optionally be interrupted by O or S. Xs1 and Xs2 may be the same or different, preferably the same. In a first preferred embodiment Xs1 and Xs2 are C1-C6 alkanediyl, more preferably C1-C4 alkanediyl, most preferably methanediyl, ethanediyl or propanediyl. In a second preferred embodiment heteroatoms are present and Xs1 and Xs2 may be -(CHR41)q -[Q- (CHR41)r]v-, with Q being selected from O or S wherein q + r ■ v is the number of C atoms in the spacer. Particularly preferred is a spacer with Q=O and q=r = 1 or 2.

Rs11 is a monovalent group of formula -(O-CH2-CHRs41)m-ORs42 , wherein m is an integer of from to 250, preferably 3 to 120, most preferably 10 to 65. Since Rs11 may be prepared by polyalkoxylation of one or more alkylene oxides it is also referred to herein as "polyalkylene oxide " or "polyoxyalkylene ". Rs41 is selected from H and a linear or branched C1 to C5 alkyl, WO 2019/185468 PCT/EP2019/057205 preferably from H and a linear or branched C1 to C3 alkyl, more preferably from H, methyl, ethyl and n-propyl, most preferably from H or methyl. Rs42 is selected from H and a linear or branched C1-C20 alkyl, which may optionally be substituted by hydroxy, alkoxy or alkoxycarbonyl, preferably from H and a linear or branched C1 to C10 alkyl, more preferably from H and methyl, ethyl, propyl or butyl, most preferably H.

Generally, Rs12 , Rs13 , Rs14 are independently selected from H, Rs11 and Rs4 °, preferably from Rs11 and Rs4 °, most preferably from Rs11 .

Rs4 ° is a linear or branched C1-C20 alkyl. Preferably Rs4 ° is C1-C10 alkyl, even more preferably C1-C6 alkyl, most preferably methyl, ethyl or propyl.

Rs42 is a linear or branched C1-C20 alkyl, which may optionally be substituted by hydroxy, alkoxy or alkoxycarbonyl. Preferably Rs42 is an unsubstituted linear or branched C1-C20 alkyl.

Generally, Rs15 is selected from H, Rs11 , Rs4 °, and -XS4-N(RS21)2 with Rs21 being selected from Rs11 and Rs4 °, preferably from Rs11 .

In a preferred embodiment Rs15 is selected from Rs11 and -XS4-N(RS11)2. In another preferred embodiment Rs15 is selected from Rs40 and -Xs4-N(Rs40 )2.

In one embodiment Xs4 is a linear or branched C1 to C12 alkanediyl. Preferably XS4 is a C1 to Calkanediyl, more preferably methanediyl, ethanediyl, propanediyl or butanediyl, most preferably methanediyl or ethanediyl.

In another embodiment Xs4 is a divalent group which is selected from a C2 to C6 polyoxyalkylene group of formula -(O-CH2-CHRs41)o - (hereinafter also referred to as polyalkylene oxide group). Herein o may be an integer from 1 to 250, preferably from 2 to 120, most preferably from 5 to 65. The C2 to C6 polyoxyalkylene group may be prepared from the one or more respective alkylene oxides. Preferably the at least one C2 to C6 polyoxyalkylene group is selected from polyoxyethylen (prepared from ethylene oxide), polyoxypropylene (prepared from propylene oxide), and polyoxybutylene (prepared from butylene oxide). More preferably the polyoxyalkylene group in Xs4 is a copolymer of ethylene oxide and at least one further C3 to Calkylene oxide. The further alkylene oxide is preferably selected from propylene oxide and 1,2- butylene oxide or any isomers thereof. In another preferred embodiment the C3 to C4 alkylene oxide is selected from propylene oxide (PO). In this case EO/PO copolymer side chains are generated from the starting molecule. Such copolymers of ethylene oxide and at least one further alkylene oxide may have random, block, alternating or any other arrangement.

As used herein, "random " means that the comonomers are polymerized from a mixture and therefore arranged in a statistically manner depending on their copoymerization parameters.

WO 2019/185468 PCT/EP2019/057205 As used herein, "block " means that the comonomers are polymerized after each other to form blocks of the respective co-monomers in any predefined order. By way of example, for EO and propylene oxide (PO) comonomers such blocks may be, but are not limited to: -EOx-POy , -POX- EOy,-EOx-POy-EOz, -POx-EOy-POz, etc.. Preferred block-type alkylene oxides are -POx-EOy , and -EOx-POy-EOz wherein x is in the range of 2 to 300, y is in the range of 2 to 300, and z is in the range of 2 to 300.

In a preferred embodiment, block -POx-EOy or -EOx-POy-EOz copolymers comprising a terminal ethylene oxide block are used, wherein the PO units may be exchanged by another C4 to Calkylene oxide.

If copolymers of ethylene oxide (EO) and a further C3 to C4 alkylene oxide are used the EO content may generally be from 3 to 95 % by weight. Preferably the EO content is from 5 to 80 % by weight, more preferably from 5 to 60 % by weight, even more preferably below 50 % by weight, even more preferably below 40 % by weight, even more preferably from 5 to 40 % by weight , even more preferably from 5 to 30 % by weight, even more preferably from 6 to 25 % by weight, most preferably from 8 to 20 % by weight.

Generally, the molecular weight Mw of the suppressing agent may be from about 500 to about 30000 g/mol, preferably 2000 to 15000 g/mol. In one embodiment the molecular weight Mw of the suppressing agent is from about 500 to about 8000 g/mol, most preferably from about 15to about 3500 g/mol. In another embodiment the molecular weight Mw of the suppressing agent is from about 5000 to about 20000 g/mol, in particular from about 6000 to about 15000 g/mol.

In a first preferred embodiment a compound of formula I is used in which s is 1,2 or 3, most preferably 1 or 2; and Rs12 , Rs13 , Rs14 and Rs15 are independently selected from a C2 to Cpolyoxyalkylene group Rs11 . Such compounds may be prepared by starting from symmetric dialkylentriamines, trialkylenetetramines, tetraalkylenpentamins, such as but not limited to diethylentriamine, triethylenetetramine, dipropylentriamine, tripropylentetramine, methyl diethylentriamine, dimethyl triethylenetetramine, and the like.

In a second preferred embodiment a compound of formula I is used in which s is 1,2 or 3, most preferably 1 or 2; Rs12 , Rs13 , Rs14 are independently selected from a C2 to C6 polyoxyalkylene group Rs11 ; and Rs15 is selected from XS4-N(RS11)2. In this way, a more branched polyoxyalkylene suppressing agent is received. Such compounds may be prepared by starting from branched amine starters, such as but not limited to tris aminoethyl amine and the like.

In a third preferred embodiment n is 1,2 or 3, most preferably 1 or 2; Rs12 , Rs13 and Rs14 are selected from a C2 to C6 polyoxyalkylene group Rs11 ; and Rs15 is selected from Rs4 °, and -Xs4 - N(Rs40)2. In this way, a linear or branched suppressing agent is received which comprises, besides the polyoxyalkylene side chains, also one or more alkyl-substituents. Such compounds may be prepared by starting from linear amines as described above, wherein the secondary WO 2019/185468 PCT/EP2019/057205 amino group(s) are alkyl substituted, or starting from branched amines in which one or more amine groups are alkyl substituted, such as but not limited to tris alkylaminoethyl amine and the like.

In a fourth preferred embodiment s is 1,2 or 3, preferably 1 or 2, most preferably 1; Rs12 is selected from Rs11 ; Rs13 and Rs14 are selected from Rs4 °; and Rs15 is selected from Rs21 . Such compounds may be prepared by starting from symmetrically alkyl substituted dialkylentriamines or trialkylenetetramines, such as but not limited to N,N-dimethyl diethylenetriamine, N,N,N- trimethyl diethylenetriamine, and the like.

In a fifth preferred embodiment n is 1,2 or 3, preferably 1 or 2, most preferably 1; and Rs13 is selected from Rs11 ; and at least one of Rs12 and Rs14 is selected from Rs4 °; and Rs15 is selected from Rs21 . Such compounds may be prepared by starting from asymmetric dialkylentriamines or trialkylenetetramines, such as but not limited to 1-N-methyl diethylenetriamine, 1,3-N- dimethyl diethylenetriamine, and the like.

Particularly preferred embodiments suppressing agents of formula I are those wherein(a) Xs1 and Xs2 are ethanediyl or propanediyl, Rs11 , Rs12 , Rs13 , Rs14 , and Rs15 are a polyoxyalkylene, particularly an oxyethylene-co-oxypropylene polymer,(b) Xs1 and Xs2 are ethanediyl or propanediyl, Rs11 , Rs12 , Rs13 , and Rs14 are a polyoxyalkylene, particularly a oxyethylene-co-oxypropylene polymer, and Rs15 is C1 to C6 alkyl or a polyoxyalkylene substituted C1 to C6 alkyl, and(c) Xs1 and Xs2 are ethanediyl or propanediyl, Rs11 , Rs12 , Rs13 , and Rs14 are a polyoxyalkylene, particularly an oxyethylene-co-oxypropylene polymer, and Rs15 is a C1 to C6 amine which is further substituted by a polyoxyalkylene, particularly oxyethylene-co-oxypropylene polymers.

Levelers One or more levelers may be present in the tin or tin alloy plating bath.

On class of levelers are linear or branched polyimidazolium compounds comprising the structural unit of formula L1 Generally, RL1 and RL2 may be an H atom or an organic radical having from 1 to 20 carbon atoms. The radicals can be branched or unbranched or comprise functional groups which can, WO 2019/185468 PCT/EP2019/057205 for example, contribute to further crosslinking of the polymeric imidazolium compound. Preferably, RL1 and RL2 are each, independently of one another, hydrogen atoms or hydrocarbon radicals having from 1 to 6 carbon atoms. Most preferably RL1 and RL2 are H atoms.Generally, RL3 may be an H atom or an organic radical having from 1 to 20 carbon atoms. Preferably, RL3 is an H atom or methyl, ethyl or propyl. Most preferably RL3 is an H atom.

Generally, XL1 may be a linear, branched or cyclic aliphatic diradical selected from a C4 to Calkandiyl, which may comprise one or more continuations of the imidazolium compound by branching.

As used herein, "continuation of the polyimidazolium compound by branching " means that the respective spacer group XL1 comprises one or more, preferably one or two, groups from which a polyimidazole branch is started. Preferably, XL1 does not comprise any continuation of the polyimidazolium compound by branching, i.e. the polyimidazolium compound is a linear polymer.

In a first embodiment XL1 is C4 to C14 alkanediyl, most preferably C4 to C12 alkanediyl, which may be unsubstituted or substituted by ORL4, NRL42, and SLR4, in which RL4 is a C1 to C4 alkyl group. In a particular embodiment, XL1 is a pure hydrocarbon radical which does not comprise any functional groups.

Particularly preferred groups XL1 are selected from a linear or branched butanediyl, pentanediyl, hexanediyl, heptanediyl, octanediyl, nonanediyl, decanediyl, undecanediyl, and dodecanediyl, which may be unsubstituted or substituted by ORL4, NRL4. Particularly preferred groups XL1 are selected from linear butanediyl, hexanediyl and octanediyl.

In second embodiment, group XL1 may be a cyclic alkanediyl of formula whereinXL2 is independently selected from a C1 to C4 alkandiyl, which may be interrupted by one or two selected from O and NRL4, andXL3 is independently selected from (a) a chemical bond or (b) a C1 to C4 alkandiyl, which may be interrupted by O or NRL4׳wherein RL4 is a C1 to C4 alkyl group.

As used herein, "chemical bond " means that the respective moiety is not present but that the WO 2019/185468 PCT/EP2019/057205 adjacent moieties are bridged so as to form a direct chemical bond between these adjacent moieties. By way of example, if in X-Y-Z the moiety Y is a chemical bond then the adjacent moieties X and Z together form a group X-Z.Either XL2 or XL3 or both XL2 and XL3 may comprise one or more continuations of the imidazolium compound by branching, preferably only X2 may comprise such continuations of the imidazolium compound by branching.

In this second embodiment, most preferably one XL2 is selected from methanediyl and the other XL2 is selected from propanediyl or both XL2 are selected from ethanediyl. Particularly preferred are groups XL1 are selected from isophoronediamine, biscyclohexyldiamino methane, and methyl-cyclohexyl-diamine (MDACH).

In a third embodiment, XL1 may be a (hetero)arylalkyl diradical selected from yl2-Yl1-Yl2. Herein YL1 may be a C5 to C20 aryl group and YL2 may be independently selected from a linear or branched C1 to C6 alkanediyl. Also here, both, YL1 and YL2 may comprise one or more continuations of the imidazolium compound by branching.

Preferred groups YL1 are selected from phenyl, naphtyl, pyridyl, pyrimidyl, and furanyl, most preferably phenyl. Preferred groups YL2 are selected from a linear or branched C1 to Calkanediyl, preferably from methanediyl, ethanediyl, 1,3-propanediyl and 1,4-butanediyl.

The organic radical XL1 may comprise not only carbon and hydrogen but also heteroatoms such as oxygen, nitrogen, sulfur or halogens, e.g. in the form of functional groups such as hydroxyl groups, ether groups, amide groups, aromatic heterocycles, primary, secondary, or tertiary amino groups or imino groups.

In particular, the organic radical XL1 may be a hydrocarbon diradical which may be substituted or interrupted by functional groups comprising heteroatoms, in particular ether groups. If substituted, it is preferred that XL1 does not comprise any hydroxyl groups.

I may generally be an integer from 2 to about 5000, preferably from about 5 to about 3000, even more preferably from about 8 to about 1000, even more preferably from about 10 to about 300, even more preferably from about 15 to about 250, most preferably from about 25 to about 150.

The mass average molecular weight Mw of the additive may generally be from 500 g/mol to 1,000,000 g/mol, preferably from 1000 g/mol to 500,000 g/mol, more preferably from 1500 g/mol to 100,000 g/mol, even more preferably from 2,000 g/mol to 50,000 g/mol, even more preferably from 3,000 g/mol to 40,000 g/mol, most preferably from 5,000 g/mol to 25,000 g/mol.

Preferably the at least one additive comprises a counterion Y0־, wherein o is a positive integer selected so that the overall additive is electrically neutral. Preferably o is 1,2 or 3. Most preferably, the counterion Y0־ is selected from chloride, sulfate, methanesulfonate or acetate.

WO 2019/185468 PCT/EP2019/057205 Preferably the number average molecular weight Mn of the polymeric imidazolium compound, determined by gel permeation chromatography, is be greater than 500 g/moL Preferably the polymeric imidazolium compound may comprise more than 80% by weight of structural units of the formula L1.

More details and alternatives are described in unpublished European patent application No. 17173987.3, patent publication WO 2016/020216 and International Patent Application No. PCT/EP2017/050054, respectively, which are incorporated herein by reference.

Other suitable leveling agents include, but are not limited to, polyaminoamide and derivatives thereof, polyalkanolamine and derivatives thereof, polyethylene imine and derivatives thereof, quaternized polyethylene imine, polyglycine, poly(allylamine), polyaniline, polyurea, polyacrylamide, poly(melamine-co-formaldehyde), reaction products of amines with epichlorohydrin, reaction products of an amine, epichlorohydrin, and polyalkylene oxide, reaction products of an amine with a polyepoxide, polyvinylpyridine, polyvinylimidazole, polyvinylpyrrolidone, or copolymers thereof, nigrosines, pentamethyl-para-rosaniline hydrohalide, hexamethyl-pararosaniline hydrohalide, or compounds containing a functional group of the formula N-R-S, where R is a substituted alkyl, unsubstituted alkyl, substituted aryl or unsubstituted aryl. Typically, the alkyl groups are C1-C6 alkyl and preferably C1-C4 alkyl. In general, the aryl groups include C6-C20 aryl, preferably C6-C12aryl. Such aryl groups may further include heteroatoms, such as sulfur, nitrogen and oxygen. It is preferred that the aryl group is phenyl or napthyl. The compounds containing a functional group of the formula N-R-S are generally known, are generally commercially available and may be used without further purification.

In such compounds containing the N-R-S functional group, the sulfur ("S") and/or the nitrogen ("N") may be attached to such compounds with single or double bonds. When the sulfur is attached to such compounds with a single bond, the sulfur will have another substituent group, such as but not limited to hydrogen, C1-C12 alkyl, C2-C12 alkenyl, C6-C20 aryl, C1-C12 alkylthio, C2- C12 alkenylthio, C6-C20 arylthio and the like. Likewise, the nitrogen will have one or more substituent groups, such as but not limited to hydrogen, C1-C12 alkyl, C2-C12 alkenyl, C7-C10 aryl, and the like. The N-R-S functional group may be acyclic or cyclic. Compounds containing cyclic N-R-S functional groups include those having either the nitrogen or the sulfur or both the nitrogen and the sulfur within the ring system.

Further leveling agents are triethanolamine condensates as described in unpublished international Patent Application No. PCT/EP2009/066581.

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In one embodiment, grain refiners may be present in the plating baths in an amount of 0.0001 to 0.045 g/l. Preferably, the grain refiners are present in an amount of 0.0001 to 0.04 g/l, more preferably in an amount of 0.0001 to 0.035 g/l, and yet more preferably from 0.0001 to 0.03 g/l. Compounds useful as the first grain refiners are generally commercially available from a variety of sources and may be used as is or may be further purified.

In another more preferred embodiment, the compositions for tin or tin alloy electroplating do comprises a single grain refiner, more preferably a single grain refiner that is no a,p ־unsaturated aliphatic carbonyl compound, most preferably essentially no grain refiner or no grain refiner at all. Surprisingly, it was found that particularly for filling recessed features having an aperture size below 50 pm there is no need to use any grain refiners but the suppressing agent leads to a good coplanarity without the use of any grain refiner.

The present compositions may optionally include further additives, such as antioxidants, organic solvents, complexing agents, and mixtures thereof.

Antioxidants Antioxidants may optionally be added to the present composition to assist in keeping the tin in a soluble, divalent state. It is preferred that one or more antioxidants are used in the present compositions. Exemplary antioxidants include, but are not limited to, hydroquinone, and hydroxylated and/or alkoxylated aromatic compounds, including sulfonic acid derivatives of such aromatic compounds, and preferably are: hydroquinone; methylhydroquinone; resorcinol; catechol; 1,2,3-trihydroxybenzene; 1,2-dihydroxybenzene-4-sulfonic acid; 1,2- dihydroxybenzene-3, 5-disulfonic acid; 1,4-dihydroxybenzene-2-sulfonic acid; 1,4- dihydroxybenzene-2, 5-disulfonic acid; 2,4-dihyroxybenzene sulfonic acid, and p- Methoxyphenol. Such antioxidants are disclosed in US 4,871,429. Other suitable antioxidants or reducing agents include, but are not limited to, vanadium compounds, such as vanadylacetylacetonate, vanadium triacetylacetonate, vanadium halides, vanadium oxyhalides, WO 2019/185468 PCT/EP2019/057205 vanadium alkoxides and vanadyl alkoxides. The concentration of such reducing agent is well known to those skilled in the art, but is typically in the range of from 0.1 to 10 g/l, and preferably from 1 to 5 g/l. Such antioxidants are generally commercially available from a variety of sources.

Electrolyte In general, as used herein "aqueous " means that the present electroplating compositions comprises a solvent comprising at least 50 % of water. Preferably, "aqueous " means that the major part of the composition is water, more preferably 90% of the solvent is water, most preferably the solvent essentially consists of water. Any type of water may be used, such as distilled, deinonized or tap.

Tin The tin ion source may be any compound capable of releasing metal ions to be deposited in the electroplating bath in sufficient amount, i.e. is at least partially soluble in the electroplating bath. It is preferred that the metal ion source is soluble in the plating bath. Suitable metal ion sources are metal salts and include, but are not limited to, metal sulfates, metal halides, metal acetates, metal nitrates, metal fluoroborates, metal alkylsulfonates, metal arylsulfonates, metal sulfamates, metal gluconates and the like.

The metal ion source may be used in the present invention in any amount that provides sufficient metal ions for electroplating on a substrate. When the metal is solely tin, the tin salt is typically present in an amount in the range of from about 1 to about 300 g/l of plating solution. In a preferred embodiment the plating solution is free of lead, that is, they contain 1 wt % lead, more preferably below 0.5 wt %, and yet more preferably below 0.2 wt%, and still more preferably are free of lead. In another preferred embodiment the plating solution is essentially free of copper, that is, they contain below 1 wt % copper, more preferably below 0.1 wt %, and yet more preferably below 0.01 wt%, and still more preferably are free of copper.

Silver Besides tin, the plating baths according to the invention contains silver ions and optionally one or more other alloying metal ions. Suitable alloying metals include, without limitation, gold, copper, bismuth, indium, zinc, antimony, manganese and mixtures thereof. Preferred alloying metals are copper, bismuth, indium, and mixtures thereof. Any bath-soluble salt of silver and other alloying metal (together referred to as alloying metal) may suitably be used as the source of alloying silver and other alloy metal ions. Examples of such alloying metal salts include, but are not limited to: metal oxides; metal halides; metal fluoroborate; metal sulfates; metal alkanesulfonates such as metal methanesulfonate, metal ethanesulfonate and metal propanesulfonate; metal arylsulfonates such as metal phenylsulfonate, metal toluenesulfonate, and metal phenolsulfonate; metal carboxylates such as metal gluconate and metal acetate; and WO 2019/185468 PCT/EP2019/057205 the like. Preferred alloying metal salts are metal sulfates; metal alkanesulfonates; and metal arylsulfonates. When silver is added to the present compositions, a binary alloy deposit is achieved. When 2, 3 or more different alloying metals are added to the present compositions, tertiary, quaternary or higher order alloy deposits are achieved. The amount of such alloying metal used in the present compositions will depend upon the particular tin-alloy desired. The selection of such amounts of alloying metals is within the ability of those skilled in the art. It will be appreciated by those skilled in the art that when certain alloying metals besides silver are used, an additional complexing agent besides the complexing agents according to the invention may be required.

The present electroplating compositions are suitable for depositing a tin-silver-containing layer, Exemplary tin-alloy layers include, without limitation, tin-silver-copper, tin-silver-indium, tin- silver-bismuth, tin-silver-copper-antimony, tin-silver-copper-manganese, tin-silver-zinc-copper, and tin-silver-indium-bismuth. Preferably, the present electroplating compositions deposit pure tin-silver, tin-silver-copper, tin-indium, tin-silver-bismuth, tin-silver-indium, and tin-silver-indium- bismuth, and more preferably pure tin-silver.

Silver alloys deposited from the present electroplating bath contain an amount of tin ranging from 0.01 to 99.99 wt %, and an amount of one silver and optionally other alloying metals ranging from 99.99 to 0.01 wt %, based on the weight of the alloy, as measured by either atomic adsorption spectroscopy (AAS), X-ray fluorescence (XRF), inductively coupled plasma mass spectrometry (ICP-MS). Preferably, the tin-silver alloys deposited using the present invention contain from 90 to 99.99 wt % tin and 0.01 to 10 wt % of silver and any other alloying metal. More preferably, the tin-silver alloy deposits contain from 95 to 99.9 wt % tin and 0.1 to 5 wt % of silver and any other alloying metal. Tin-silver alloy is the preferred tin-alloy deposit, and preferably contains from 90 to 99.9 wt % tin and from 10 to 0.1 wt % silver. More preferably, the tin-silver alloy deposits contain from 95 to 99.9 wt % tin and from 5 to 0.1 wt % silver. For many applications, the eutectic composition of an alloy may be used. Alloys deposited according to the present invention are substantially free of lead, that is, they contain 1 wt % lead, more preferably below 0.5 wt %, and yet more preferably below 0.2 wt%, and still more preferably are free of lead.

Bath In general, besides the metal ion source and at least one of the complexing agents, the present metal electroplating compositions preferably include electrolyte, i. e. acidic or alkaline electrolyte, one or more sources of metal ions, optionally halide ions, and optionally other additives like surfactants and grain refiners. Such baths are typically aqueous. The water may be present in a wide range of amounts. Any type of water may be used, such as distilled, deionized or tap.

WO 2019/185468 PCT/EP2019/057205 Preferably, the plating baths of the invention are acidic, that is, they have a pH below 7. Typically, the pH of the tin or tin alloy electroplating composition is below 4, preferably below 3, most preferably below 2.

The electroplating baths of the present invention may be prepared by combining the components in any order. It is preferred that the inorganic components such as metal salts, water, electrolyte, are first added to the bath vessel followed by the organic components such as surfactants, grain refiners, levelers and the like.

Typically, the plating baths of the present invention may be used at any temperature from 10 to degrees C or higher. It is preferred that the temperature of the plating baths is from 10 to degrees C and more preferably from 15 degrees to 30 degrees C.

Suitable electrolytes include such as, but not limited to, sulfuric acid, acetic acid, fluoroboric acid, alkylsulfonic acids such as methanesulfonic acid, ethanesulfonic acid, propanesulfonic acid and trifluoromethane sulfonic acid, arylsulfonic acids such as phenyl sulfonic acid and toluenesulfonic acid, sulfamic acid, hydrochloric acid, phosphoric acid, tetraalkylammonium hydroxide, preferably tetramethylammonium hydroxide, sodium hydroxide, potassium hydroxide and the like. Acids are typically present in an amount in the range of from about 1 to about 3g/i.

In one embodiment the at least one additive comprises a counterion Y0־ selected from methane sulfonate, sulfate or acetate, wherein o is a positive integer.

Application The plating compositions of the present invention are useful in various plating methods where a tin-containing layer is desired, and particularly for depositing a tin-containing solder layer on a semiconductor wafer comprising a plurality of conductive bonding features. Plating methods include, but are not limited to, horizontal or vertical wafer plating, barrel plating, rack plating, high speed plating such as reel-to-reel and jet plating, and rackless plating, and preferably horizontal or vertical wafer plating. A wide variety of substrates may be plated with a tin- containing deposit according to the present invention. Substrates to be plated are conductive and may comprise copper, copper alloys, nickel, nickel alloys, nickel-iron containing materials. Such substrates may be in the form of electronic components such as (a) lead frames, connectors, chip capacitors, chip resistors, and semiconductor packages, (b) plastics such as circuit boards, and (c) semiconductor wafers. Preferably the substrates are semiconductor wafers. Accordingly, the present invention also provides a method of depositing a tin-containing layer on a semiconductor wafer comprising: providing a semiconductor wafer comprising a plurality of conductive bonding features; contacting the semiconductor wafer with the composition described above; and applying sufficient current density to deposit a tin-containing layer on the conductive bonding features. Preferably, the bonding features comprise copper, WO 2019/185468 PCT/EP2019/057205 which may be in the form of a pure copper layer, a copper alloy layer, or any interconnect structure comprising copper. Copper pillars are one preferred conductive bonding feature. Optionally, the copper pillars may comprise a top metal layer, such as a nickel layer. When the conductive bonding features have a top metal layer, then the pure tin solder layer is deposited on the top metal layer of the bonding feature. Conductive bonding features, such as bonding pads, copper pillars, and the like, are well-known in the art, such as described in US 7,781,325, US 2008/0054459 A, US 2008/0296761 A, and US 2006/0094226 A.

Process In general, when the present invention is used to deposit tin alloys on a substrate the plating baths are agitated during use. Any suitable agitation method may be used with the present invention and such methods are well-known in the art. Suitable agitation methods include, but are not limited to, inert gas or air sparging, work piece agitation, impingement and the like. Such methods are known to those skilled in the art. When the present invention is used to plate an integrated circuit substrate, such as a wafer, the wafer may be rotated such as from 1 to 1RPM and the plating solution contacts the rotating wafer, such as by pumping or spraying. In the alternative, the wafer need not be rotated where the flow of the plating bath is sufficient to provide the desired metal deposit.

The tin alloy is deposited in recesses according to the present invention without substantially forming voids within the metal deposit. By the term "without substantially forming voids", it is meant that there are no voids in the metal deposit which are bigger than 1000 nm, preferably 500 nm, most preferably 100 nm.

Plating equipment for plating semiconductor substrates are well known. Plating equipment comprises an electroplating tank which holds tin or tin alloy electrolyte and which is made of a suitable material such as plastic or other material inert to the electrolytic plating solution. The tank may be cylindrical, especially for wafer plating. A cathode is horizontally disposed at the upper part of tank and may be any type substrate such as a silicon wafer having openings.

These additives can be used with soluble and insoluble anodes in the presence or absence of a membrane or membranes separating the catholyte from the anolyte.

The cathode substrate and anode are electrically connected by wiring and, respectively, to a power supply. The cathode substrate for direct or pulse current has a net negative charge so that the metal ions in the solution are reduced at the cathode substrate forming plated metal on the cathode surface. An oxidation reaction takes place at the anode. The cathode and anode may be horizontally or vertically disposed in the tank.

In general, when preparing tin alloy bumps, a photoresist layer is applied to a semiconductor wafer, followed by standard photolithographic exposure and development techniques to form a WO 2019/185468 PCT/EP2019/057205 patterned photoresist layer (or plating mask) having openings or vias therein. The dimensions of the plating mask (thickness of the plating mask and the size of the openings in the pattern) defines the size and location of the tin or tin alloy layer deposited over the I/O pad and UBM. The diameter of such deposits typically range from 1 to 300 pm, preferably in the range from to 100 pm.

All percent, ppm or comparable values refer to the weight with respect to the total weight of the respective composition except where otherwise indicated. All cited documents are incorporated herein by reference.

The following examples shall further illustrate the present invention without restricting the scope of this invention.

Examples Example 1: Preparation of complexing agents Example 1.1: 1,8-Bis(2-pyridyl)-3,6-dithiaoctane To a solution of 346.8 g 2-vinylpyridine in 200 ml iso-propanol were added at 50°C 153.8 g of 1,2-ethanedithiol under inert atmosphere. Then the reaction mixture was heated to reflux. After hours of stirring at reflux the temperature was reduced to 60°C. The warm solution was then stirred into 1000 ml of 10°C cold petroleum ether. The precipitate was filtered off and dried in vacuo at 35°C to yield 417.3 g of 1,8-bis(2-pyridyl)-3,6-dithiaoctane as a colourless solid (mp. 48,9-49,4°C; assay by GC 99.5%).

Example 1.2: 1,9-Bis-(3-pyridyl)-2,5,8-trithianonane Under inert atmosphere 14.3 g of a 21 % solution of sodium ethylate in ethanol were put into ml of dry ethanol at 0 to 5°C. Then 1.71 g of bis-(2-mercaptoethyl)-sulfide were added at 0 to 4°C followed by the addition of a solution of 5.20 g 3-(bromomethyl)-pyridine hydrobromide in ml of ethanol and three drops of water at -8 to 4°C. After stirring overnight at room temperature the reaction mixture was concentrated in vacuo. The residue was diluted with 30 ml of dichloromethane and extracted with 30 ml of water. The aqueous phase was extracted again four times each with 30 ml of dichloromethane and the collected organic phases were dried over sodium sulfate. After filtration and concentration in vacuo the crude product was purified by chromatography over silica gel with cyclohexane and ethyl acetate as the eluents (eluation with WO 2019/185468 PCT/EP2019/057205 a gradient) to yield 2.3 g of 1,9-bis-(3-pyridyl)-2,5,8-trithia-nonane as a light yellow oil (mp 55,3°C-55,6°C, assay by C-NMR >95%).

Example 1.3: 1,13-Bis(2-pyridyl)-2,5,9,12-tetrathiatridecane Under inert atmosphere 14.3 g of a 21 % solution of sodium ethylate in ethanol were put into ml of dry ethanol at 0 to 5°C. Then 1.94 ml of 3,7-dithia-nonane-1,9-dithiol were added at 0 to 4°C followed by the addition of a solution of 3.28 g 2-(chloromethyl)-pyridine hydrochloride in ml of dry ethanol at -8 to 4°C. After stirring overnight at room temperature the reaction mixture was concentrated in vacuo. The residue was diluted with 50 ml of dichloromethane and extracted with 50 ml of water. The aqueous phase was extracted again three times each with ml of dichloromethane and the collected organic phases were dried over sodium sulfate. After filtration and concentration in vacuo 3.81 g of 1,9-bis-(2-pyridyl)-2,5,9,12-tetrathiadodecane were obtained as a brownish oil (assay by C-NMR >95%).

Example 1.4: (2R,3R)-1,4-bis[2-(2-pyridyl)ethylsulfanyl]butane-2,3-diol / (2S,3S)-1,4-bis[2-(2- pyridyl)-ethylsulfanyl]butane-2,3-diol To a solution of 1.54 g DL-dithiothreitol in 50 ml ethanol were added 2.17 g 2-vinylpyridine and the reaction mixture was heated to reflux for 7 hours. The reaction mixture was then stirred overnight at room temperature. After that the reaction mixture was concentrated in vacuo to yield 3.7 g of 1,4-bis[2-(2-pyridyl)ethylsulfanyl]butane-2,3-diol (DL) as a viscous oil, which solidifies when cooling to room temperature (mp. 92,8-93,4°C assay by C-NMR >95 %).

Example 1.5: 1,6-Bis(2-methylpyridyl)-meso-dithioerythritol OH To a solution of 14.30 g of a 21 % solution of sodium ethylate in 20 ml of dry ethanol were added 1.54 g of meso-dithioerythritol at 0 to 5°C within 10 minutes under inert atmosphere. Then a solution of 3.28g 2-(chloromethyl)-pyridine hydrochloride in 50 ml of dry ethanol was added at -to 5°C. When the addition was finished the reaction mixture was let to come to room temperature, stirred overnight at room temperature and concentrated in vacuo. The residue was diluted with 50 ml of dichloromethane and extracted with 50 ml of water. The aqueous phase WO 2019/185468 PCT/EP2019/057205 was extracted again three times each with 50 ml of dichloromethane and the collected organic phases were dried over sodium sulfate. After filtration and concentration in vacuo 3.5 g of 1,6- bis(2-methylpyridyl)-meso-dithioerythritol were obtained as a beige solid (mp. 101,5-102,3°C; assay by C-NMR 90-95%).

Example 1.6: 1,11-Bis(2-pyridyl)-6-oxa-3,9-dithiaundecane To a solution of 173.4g 2-vinylpyridine in 170 ml iso-propanol 116.4 g di-(2-mercaptoethyl)-ether were added under inert atmosphere. Then the reaction mixture was heated to reflux. After stirring for 7 hours at reflux the reaction mixture was cooled to room temperature and concentrated in vacuo. The crude product was then washed three times with 150 ml petrolether each time to yield 289.9g of 1,11-bis(2-pyridyl)-6-oxa-3,9-dithiaundecane as a brownish viscous oil (assay by GC 97.6%).

Example 1.7: 1,8-Bis(4-pyridyl)-3,6-dithiaoctane To a solution of 9.42g of 1,2-ethanedithiol in 40ml iso-propanol were added 21.68g 4- vinylpyridine under inert atmosphere. Then the reaction mixture was heated to reflux. After stirring overnight at reflux the temperature was reduced to room temperature and the reaction mixture was concentrated in vacuo. Then the residue was stirred into 150 ml of petroleum ether. The precipitate was filtered off and dried in vacuo at 35°C to yield 30.3g of 1,8-bis(4-pyridyl)- 3,6-dithiaoctane as a beige solid (mp. 69.5-70°C; assay by GC 99.5%).

Example 1.8: 1,14-Bis(2-pyridyl)- 6,9-dioxa-3,12-dithiatetradecane To a solution of 173.4 g 2-vinylpyridine in 170 ml iso-propanol 153.5 g 3,6-dioxa-1,8-octane- dithiol were added under inert atmosphere. Then the reaction mixture was heated to reflux. After stirring for 7 hours at reflux the reaction mixture was cooled to room temperature, concentrated in vacuo, washed three times each with 100 ml petroleum ether and concentrated again in vacuo to yield 310,33 g of 1,14-Bis(2-pyridyl)- 6,9-dioxa-3,12-dithiatetradecane as a brownish viscous oil (assay by GC 96.4%).

WO 2019/185468 PCT/EP2019/057205 Example 1.9: 1,15-Bis(4-pyridyl)-3,6,10,13-tetrathiapentadecane To a solution of 2.17g 4-vinylpyridine in 50 ml iso-propanol were added 2.28 g 3,7-dithia- nonane-1,9-dithiol. Then the reaction mixture was heated to reflux. After stirring 8,5 h at reflux the reaction mixture was cooled to room temperature and concentrated in vacuo. The oily residue was purified by chromatography on silica gel with dichloromethane/methanol as the eluents (eluation with a gradient) to yield 3.4 g of 1,15-bis(4-pyridyl)-3,6,10,13- tetrathiapentadecane as a colourless solid (mp. 54,5-56,2°C; assay by C-NMR >95%).

Example 1.10: (2R,3S)-1,4-bis[2-(4-pyridyl)ethylsulfanyl]butane-2,3-diol To a solution of 177.1 g 4-vinylpyridine in 170 ml iso-propanol were added 124.7 g meso- dithioerythritol. Then the reaction mixture was heated to reflux. After stirring 7 hours at reflux the reaction mixture was cooled to 50°C and then fed into 1500 ml 15°C cold water. The precipitate was filtered off and dried in vacuo at 60°C to yield 284.4 g of (2R,3S)-1,4-bis[2-(4- pyridyl)ethylsulfanyl]butane-2,3-diol as a white powder (mp. 119.4-120,8 °C; assay by GC 98.7%).

Example 1.11: 1-[2-[2-(2-imidazol-1-ylethylsulfanyl)ethylsulfanyl]ethyl]imidazole Under inert atmosphere 79.8 g KOH were dissolved in 1200 ml ethanol. Then 25.9 g 1,2- ethanethiol were added. After stirring 1 hour at room temperature 94.7 g 1-(2-chloroethyl)- imidazole hydrochloride were added. The reaction mixture was heated up and stirred for 5.hours at 60°C. While cooling down to room temperature the reaction mixture was stirred overnight. After concentration in vacuo the residue was diluted with 250 ml dichloromethane and extracted with 250 ml of water. The aqueous phase was extracted again three times each with 250 ml dichloromethane and the collected organic phases were dried over sodium sulfate. After filtration and concentration in vacuo the crude product was purified by chromatography over silica gel with dichloromethane and methanol as the eluents (eluation with a gradient) to yield 49.5g of 1-[2-[2-(2-imidazol-1-ylethylsulfanyl)ethylsulfanyl]ethyl]imidazole as a beige solid (mp. 44,4-46,0°C; assay by C-NMR >95%).

WO 2019/185468 PCT/EP2019/057205 Example 1.12: 1-methyl-2-[2-[2-[2-(1-methylpyridin-1-ium-2-yl)ethylsulfanyl]ethylsulfanyl]ethyl] pyridin-1-ium;methyl sulfate To a solution of 4,56g 1,8-Bis(2-pyridyl)-3,6-dithiaoctane in 20ml acetonitrile was added 2,84 ml dimethyl sulfate. The reaction mixture was then stirred at 45°C for 27h and stirring was continued overnight at room temperature. The reaction mixture was concentrated in vacuo to yield 8,4g of 1-methyl-2-[2-[2-[2-(1-methylpyridin-1-ium-2-yl)ethylsulfanyl]ethylsulfanyl]ethyl] pyridin-1-ium;methyl sulfate as a viscous oil, which solidified while standing (mp. 46,4-47,9°C assay by C-NMR >95 %).

Example 1.13: 1,13-Bis(3-pyridyl)-2,5,9,12-tetrathiatridecane Under inert atmosphere 14.3 g of a 21 % solution of sodium ethylate in ethanol were put into ml of dry ethanol at 0 to 5°C. Then 1.94 ml of 3,7-dithia-nonane-1,9-dithiol were added at -4 to 4°C followed by the addition of a solution of 5.06 g 3-(bromomethyl)-pyridine hydrobromide in ml of ethanol at -4 to 5°C. After stirring overnight at room temperature the reaction mixture was concentrated in vacuo. The residue was diluted with 50 ml of dichloromethane and extracted with 50 ml of water. The aqueous phase was extracted again three times each with ml of dichloromethane and the collected organic phases were dried over sodium sulfate. After filtration and concentration in vacuo the crude product was purified by chromatography over silica gel with dichloromethane and methanol as the eluents (eluation with a gradient) to yield 2.26 g of 1,13-Bis(3-pyridyl)-2,5,9,12-tetrathiatridecane as a yellowish oil (assay by C-NMR > 95%).

Example 1.14: 1,13-Bis(4-pyridyl)-2,5,9,12-tetrathiatridecane WO 2019/185468 PCT/EP2019/057205 Under inert atmosphere 14.3 g of a 21 % solution of sodium ethylate in ethanol were put into ml of dry ethanol at 0 to 5°C. Then 1.94 ml of 3,7-dithia-nonane-1,9-dithiol were added at -4 to 4°C followed by the addition of a solution of 3.28 g 4-(chloromethyl)-pyridine hydrochloride in ml of ethanol with three drops of water at 0 to 4°C. After stirring overnight at room temperature the reaction mixture was concentrated in vacuo. The residue was diluted with 50 ml of dichloromethane and extracted with 30 ml of water. The aqueous phase was extracted again three times each with 50 ml of dichloromethane and the collected organic phases were dried over sodium sulfate. After filtration and concentration in vacuo the crude product was purified by chromatography over silica gel with dichloromethane and methanol as the eluents (eluation with a gradient) to yield 2.40 g of 1,13-bis(4-pyridyl)-2,5,9,12-tetrathiatridecane as a yellowish oil (assay by C-NMR > 95%).

Example 1.15: 1-[3-[2-[2-(3-imidazol-1-ylpropylsulfanyl)ethylsulfanyl]ethylsulfanyl]propyl]-imidazole To a solution of 2.21 ml 1-allylimidazole in 20 ml of iso-propanol were added 1.31 g 2,2’-thiodi- ethanethiol and 164 mg Al BN. Then the reaction mixture was heated to reflux. After stirring hours at reflux the reaction mixture was cooled to room temperature and stirred overnight. After concentration in vacuo the oily residue was purified by chromatography on silica gel with dichloromethane/methanol as the eluents (eluation with a gradient) to yield 1.1 g of 1-[3-[2-[2-(3- imidazol-1-ylpropylsulfanyl)ethylsulfanyl]ethylsulfanyl]propyl]imidazole as a colourless oil. (assay by C-NMR 80-90%).

Example 1.16: (2S,3R)-1,4-bis(3-imidazol-1 -ylpropylsulfanyl)butane-2,3-diol To a solution of 2.21 ml 1-allylimidazole in 20 ml iso-propanol were added 1.56 g meso-dithio- erythritol and 164 mg AIBN. Then the reaction mixture was heated to reflux. After stirring 4.hours at reflux another 164 mg AIBN were added and the stirring was continued overnight at reflux. Then 164 mg AIBN were added and after 4 hours of stirring at reflux another 164 mg AIBN. After stirring 4 more hours at reflux the reaction mixture was let to cool to room temperature while stirring overnight. After concentration in vacuo the crude product was purified by chromatography over silica gel with dichloromethane and methanol as the eluents (eluation with a gradient) to yield 1.7 g of (2S,3R)-1,4-bis(3-imidazol-1-ylpropylsulfanyl)butane-2,3-diol as a slightly yellowish oil. (assay by C-NMR 85-90%).

WO 2019/185468 PCT/EP2019/057205 Example 1.17: (2R,3S)-1,4-bis(2-morpholinoethylsulfanyl)butane-2,3-diol on Under inert atmosphere 14.3 g of a 21% solution of sodium ethylate in ethanol were put into ml of dry ethanol at 0 to 5°C. Then 1.54 g meso-dithioerythritol were added at 0 to 4°C followed by the addition of a solution of 3.72 g 4-(2-chloroethyl)morpholine hydrochloride in 50 ml of dry ethanol at -7 to 4°C. After stirring overnight at room temperature the reaction mixture was concentrated in vacuo. The residue was diluted with 50 ml dichloromethane and extracted with ml of water. The aqueous phase was extracted again four times with dichloromethane and the collected organic phases were dried over sodium sulfate. After filtration and concentration in vacuo the crude product was purified by chromatography over silica gel with dichloromethane and methanol as the eluents (eluation with a gradient) and 1.9 g of (2R,3S)-1,4-bis(2- morpholinoethylsulfanyl)butane-2,3-diol were obtained as a slightly yellowish solid (mp. 88,0- 89,1 °C; assay by C-NMR > 95%).

Example 1.18: (2R,3S)-1,4-bis(2-imidazol-1 -ylethylsulfanyl)butane-2,3-diol To a solution of 1.56 g meso-dithioerythritol in 20 ml iso-propanol were added under inert atmosphere 1.85 ml 1-vinylimidazol and 164 mg AIBN. Then the reaction mixture was heated to reflux. After stirring 6 hours at reflux the stirring was continued overnight at room temperature. The precipitated product was filtered off, washed with petroleum ether and dried in vacuo to yield 2.66 g of (2R,3S)-1,4-bis(2-imidazol-1-ylethylsulfanyl)butane-2,3-diol as a slightly yellow solid (mp. 135,4-140,8°C; assay by C-NMR 85-90%).

Example 1.19: 1-[2-[(2R,3S)-2,3-dihydroxy-4-[2-(2-oxopyrrolidin-1-yl)ethylsulfanyl]butyl]sulfanyl- ethyl]pyrrolidin-2-one To a solution of 1.56 g meso-dithioerythritol in 20 ml iso-propanol were added under inert atmosphere 2.18 ml 1-vinylpyrrolidone. Then the reaction mixture was heated to reflux. After stirring 6 hours at reflux the stirring was continued overnight at room temperature. After WO 2019/185468 PCT/EP2019/057205 concentration in vacuo the crude product was purified by chromatography over silica gel with dichloromethane and methanol as the eluents (eluation with a gradient) to yield 2.6 g of 1-[2- [(2R,3S)-2,3-dihydroxy-4-[2-(2-oxopyrrolidin-1-yl)ethylsulfanyl]butyl]sulfanylethyl]pyrrolidin-2-one as a white solid (mp. 104,1-106,0°C; assay by C-NMR >95%).

Example 1.20: 2,2-bis[3-[2-(2-pyridyl)ethylsulfanyl]propoxymethyl]butan-1 -ol To a solution of 1g 2,2-bis(3-sulfanylpropoxymethyl)butan-1-ol in 20 ml iso-propanol were added 0,79 ml 2-vinylpyridine. After stirring 7 hours at reflux the reaction mixture was cooled to room temperature and stirred overnight. After concentration in vacuo the oily residue was purified by chromatography on silica gel with dichloromethane/methanol as the eluents (eluation with a gradient) to yield 0.9 g of 2,2-bis[3-[2-(2-pyridyl)ethylsulfanyl] propoxymethyl]butan-1-ol as a colourless oil (assay by C-NMR >95%).

Starting material of example 20:2,2-bis(3-sulfanylpropoxymethyl)butan-1-ol 0,12 g AIBN and 5,15 ml thioacetic acid were added to 6,49 g trimethylolpropane-diallylether at room temperature and the reaction mixture was stirred overnight at 70°C. The reaction mixture was then stirred overnight at room temperature. After that excess of thioacetic acid was evaporated in vacuo. Next, 100 ml methanol and 12 ml concentrated hydrochloric acid were added and the reaction was heated to reflux for 3 hours. Then, methanol was removed under vacuum. The residue was diluted with 50 ml water and 50 ml dichloromethane. The aqueous phase was extracted three times with 50 ml of dichloromethane and the collected organic phases were dried over sodium sulfate. After filtration and concentration in vacuo the crude product was purified by chromatography over silica gel with dichloromethane as the eluent (eluation with a gradient) and 1,6 g of 2,2-bis(3-sulfanylpropoxymethyl)butan-1-ol were obtained as a yellowish oil (assay by C-NMR > 90%).

Example 1.21: 1 -[2-[2-[2-(2-imidazol-1 -ylethylsulfanyl)ethylsulfanyl]ethylsulfanyl]ethyl]imidazole WO 2019/185468 PCT/EP2019/057205 To a solution of 33,8 g 2,2’-thiodiethanethiol in 100 ml iso-propanol were added under inert atmosphere 41,29 g 1-vinylimidazol and 0,49 mg AIBN. Then the reaction mixture was heated to reflux. After stirring 6 hours at reflux the stirring was continued overnight at room temperature. After concentration in vacuo the crude product was purified by chromatography over silica gel with dichloromethane/methanol as the eluent (eluation with a gradient) to yield g of 1-[2-[2-[2-(2-imidazol-1-ylethylsulfanyl)ethylsulfanyl] ethylsulfanyljethyljimidazole as a yellow oil (assay by C-NMR > 90%).

Example 1.22: 1,10-Bis(2-pyridyl)-3,8-dithiadecane To a solution of 2,33 ml 1,4-butanedithiol in 25 ml iso-propanol were added 4,44 ml 2- vinylpyridine. After stirring 7 hours at reflux the reaction mixture was cooled to room temperature and stirred overnight. After concentration in vacuo the residue was purified by chromatography on silica gel with dichloromethane/methanol as the eluents (eluation with a gradient) to yield 5.3 g of 1,10-Bis(2-pyridyl)-3,8-dithiadecane as a yellowish oil. (assay by C- NMR >95%).

Example 1.23: (2R,3S)-1,4-bis(2-pyrazin-2-ylethylsulfanyl)butane-2,3-diol ,15 ml of a 21 % solution of sodium ethylate in ethanol were put into a solution of 1,54g meso- dithioerythritol in ethanol. After stirring 30min at room temperature 2,08 ml 2-vinylpyrazine were added and the reaction mixture was stirred overnight at room temperature. After concentration in vacuo the crude product was purified by chromatography over silica gel with dichloromethane and methanol as the eluents (eluation with a gradient) and 2.3 g of (2R,3S)-1,4-bis(2-pyrazin-2- ylethylsulfanyl)butane-2,3-diol were obtained as a yellow solid (assay by C-NMR > 95%).

Example 1.24: (2R,3S)-1,4-bis(2-thiazol-2-ylpropylsulfanyl)butane-2,3-diol WO 2019/185468 PCT/EP2019/057205 To a solution of 1,54 ml meso-dithioerythritol in 20 ml iso-propanol were added 2,37 ml 2- isopropenyl thiazole. After stirring 7,5 hours at reflux the reaction mixture was cooled to room temperature and stirred overnight. After concentration in vacuo the residue was purified by chromatography on silica gel with dichloromethane/methanol as the eluents (eluation with a gradient) to yield 1.2 g of (2R,3S)-1,4-bis(2-thiazol-2-ylpropylsulfanyl)butane-2,3-diol as a red oil (assay by C-NMR >95%).

Example 1.25: 3-[2-(2-pyridyl)ethyl]-5-[2-(2-pyridyl)ethylsulfanyl]-1,3,4-thiadiazole-2-thione OCT^-0 To a solution of 1,53 ml 1,3,4-thiadiazole-2,5-dithiol in 20 ml iso-propanol were added 2,22 ml 2- vinylpyridine and further 60ml iso-propanol. After stirring 7,5 hours at reflux the reaction mixture was cooled to room temperature and stirred overnight. After concentration in vacuo the residue was purified by chromatography on silica gel with dichloromethane/methanol as the eluents (eluation with a gradient) to yield 2.4 g of 3-[2-(2-pyridyl)ethyl]-5-[2-(2-pyridyl)ethylsulfanyl]- 1,3,4-thiadiazole-2-thione as a yellow oil (assay by C-NMR >90%).

Example 1.26: 2,3-bis[2-(2-pyridyl)ethylsulfanyl]propan-1-ol To a solution of 1,27 ml 2,3-dimercaptopropanol in 25 ml iso-propanol were added 2,17 ml 2- vinylpyridine. After stirring 7 hours at reflux the reaction mixture was cooled to room temperature and stirred overnight. After concentration in vacuo the residue was purified by chromatography on silica gel with dichloromethane/methanol as the eluents (eluation with a WO 2019/185468 PCT/EP2019/057205 gradient) to yield 2.4 g of 2,3-bis[2-(2-pyridyl)ethylsulfanyl]propan-1-ol as a yellow oil (assay by C-NMR >95%).

Example 1.27: 6,8-bis[2-(2-pyridyl)ethylsulfanyl]octanoic acid To a solution of 1 g DL-6,8-thiociticacid in 20 ml iso-propanol were added 1,05 ml 2- vinylpyridine. After stirring 7 hours at reflux the reaction mixture was cooled to room temperature and stirred overnight. After concentration in vacuo the residue was purified by chromatography on silica gel with dichloromethane/methanol as the eluents (eluation with a gradient) to yield 1.1 g of 6,8-bis[2-(2-pyridyl)ethylsulfanyl]octanoic acid as a yellow oil (assay by C-NMR >95%).

Example 1.28: 2-[2-[[5-[2-(2-pyridyl)ethylsulfanylmethyl]-1,4-dithian-2-yl]methylsulfanyl]- To a solution of 2,21 g 1,4-dithiane-2,5-di(methanethiol) in 25 ml iso-propanol were added 2,ml 2-vinylpyridine. After stirring 7 hours at reflux the reaction mixture was cooled to room temperature and stirred overnight. After concentration in vacuo the residue was purified by chromatography on silica gel with dichloromethane/methanol as the eluents (eluation with a gradient) to yield 3.1 g of 2-[2-[[5-[2-(2-pyridyl)ethylsulfanylmethyl]-1,4-dithian-2- yl]methylsulfanyl]ethyl]pyridine as a coluorless oil (assay by C-NMR 90-95%).

Example 1.29: 4,6-bis[2-(2-pyridyl)ethylsulfanyl]-1,3,5-triazin-2-amine WO 2019/185468 PCT/EP2019/057205 To a solution of 1,78 g 2-amino-1,3,5-triazine-4,6-dithiol in 25 ml DMF were added 2,22 ml 2- vinylpyridine. After stirring 7,5 hours at 86°C the reaction mixture was cooled to room temperature and stirred overnight. After concentration in vacuo the residue was purified by chromatography on silica gel with dichloromethane/methanol as the eluents (eluation with a gradient) to yield 2.4 g of 4,6-bis[2-(2-pyridyl)ethylsulfanyl]-1,3,5-triazin-2-amine as a brownish oil (assay by C-NMR >95%).

Example 1.30: 3-[2-[2-[(2S,3R)-2,3-dihydroxy-4-[2-[1 -(3-sulfonatopropyl)pyridine-1 -ium-2- yl]ethylsulfanyl] butyl]sulfanylethyl]pyridine-1 -ium-1 -yl]propane-1 -sulfonate To a solution of 2,3 g 1-3(sulfopropyl)-2-vinylpyridinium hydroxide inner salt in 25 ml water was added 0,77 g dithioerythritol. After stirring 7 hours at reflux the reaction mixture was cooled to room temperature and stirred overnight. The reaction mixture was concentrated in vacuo, then methanol was added. The precipitated product was filtered off, washed with methanol and dried in vacuo to yield 1.8 g of 3-[2-[2-[(2S,3R)-2,3-dihydroxy-4-[2-[1-(3-sulfonatopropyl)pyridin-1-ium- 2-yl]ethylsulfanyl]butyl]sulfanylethyl]pyridin-1-ium-1-yl]propane-1-sulfonate as a white solid (mp. 195,2-198,5°C°; assay by C-NMR 90-95%).

Example 1.31: 3-[2-[2-[2-[2-[1 -(3-Sulfonatopropyl)pyridine-1 -ium-2-yljethylsulfanyljethylsulfanyl] ethyl]pyridine-1 -ium-1 -yl]propane-1 -sulfonate To a solution of 2,3 g 1-3(sulfopropyl)-2-vinylpyridinium hydroxide inner salt in 25 ml water was added 15 ml methanol and 420 pl 1,2-ethanedithiol. After stirring 7 hours at reflux the reaction mixture was cooled to room temperature and stirred overnight. The reaction mixture was concentrated in vacuo, then methanol was added. The precipitated product was filtered off, washed with methanol and dried in vacuo to yield 1.9 g of 3-[2-[2-[2-[2-[1-(3- WO 2019/185468 PCT/EP2019/057205 sulfonatopropyl)pyridine-1-ium-2-yl]ethylsulfanyl]ethylsulfanyl]ethyl]pyridine-1-ium-1-yl]propane- 1-sulfonate as a slightly yellowish solid (mp. 246,6-248,7°C; assay by C-NMR 75-85%).

Example 1.32: 1,3-Bis[3-[2-(2-pyridyl)ethylsulfanyl]propoxy]propane-2-ol OH To a solution of 6,8 g 1,3-bis(3-sulfanylpropoxy)propane-2-ol in 30 ml iso-propanol was added 6,13 ml 2-vinylpyridine. After stirring 4 hours at reflux the reaction mixture was cooled to room temperature and stirred overnight. After concentration in vacuo the residue was purified by chromatography on silica gel with dichloromethane/methanol as the eluents (eluation with a gradient) to yield 5 g of 1,3-bis[3-[2-(2-pyridyl)ethylsulfanyl]propoxy]propane-2-ol as a yellow oil (assay by C-NMR 95%).

Example 1.33: N1 ,N3-bis[2-[2-(2-Pyridyl)ethylsulfanyl]ethyl]benzene-1,3-dicarboxamide To a suspension of 2 g emeramide in 20 ml iso-propanol was added 1,54 ml 2-vinylpyridine.After stirring 7,5 hours at reflux the reaction mixture was cooled to room temperature and stirred overnight. After concentration in vacuo the residue was purified by chromatography on silica gel with dichloromethane/methanol as the eluents (eluation with a gradient) to yield 2,6 g of N1,N3- bis[2-[2-(2-Pyridyl)ethylsulfanyl]ethyl]benzene-1,3-dicarboxamide as a light yellowish oil (assay by C-NMR >95%).

Example 1.34: 2,3-Bis[2-(2-pyridyl)ethylsulfanyl]propane-1-sulfonate-sodium salt WO 2019/185468 PCT/EP2019/057205 To a suspension of 1 g DL-2,3-dimercapto-1-propansulfonicacid-sodium salt monohydrate in ml iso-propanol was added 911 pl 2-vinylpyridine. After stirring 6 hours at reflux the reaction mixture was cooled to room temperature and stirred overnight. After concentration in vacuo the residue was purified by chromatography on silica gel with dichloromethane/methanol as the eluents (eluation with a gradient) to yield 1,6 g of 2,3-Bis[2-(2-pyridyl)ethylsulfanyl]propane-1- sulfonate-sodium salt as a colorless oil (assay by C-NMR 90%).

Example 1.35: 2-[2-[5-[2-(2-Pyridyl)ethylsulfanyl]pentylsulfanyl]ethyl]pyridine To a solution of 28,10 g 1,5-pentanedithiol in 100 ml iso-propanol was added 44,70 g 2- vinylpyridine at 84°C. After stirring 8 hours at reflux the reaction mixture was cooled to room temperature and stirred overnight. After concentration in vacuo the residue was purified by chromatography on silica gel with dichloromethane/methanol as the eluents (eluation with a gradient) to yield 57,6 g of 2-[2-[5-[2-(2-pyridyl)ethylsulfanyl]pentylsulfanyl]ethyl]pyridine as a yellow fluid (assay by C-NMR >95%).

Example 2: Stability test A silver methanesulfonic acid solution was added to the complexing agent (ratio complexing agent:Ag = 10:1). If the complexing agent was insoluble, 2-3 drops of methanesulfonic acid were added. Next, a tin methanesulfonic acid solution containing 4-methoxyphenol (MeHQ) as antioxidant was added. The mixture was then stored at 50°C for 7 days. If a precipitate was formed, the complexing agent failed the test. If the mixture stayed clear over a period of 3 days, this was an indication for a good complexation ("o "), if the mixture stayed clear over a period of days for a very good complexation ("+").

Assumed that the reaction rate at temperatures <100°C is tripled when the temperature is increased by 10°C, 7 days at 50°C should reflect the stability of 6 months at 20°C.

The complexing agents of example 1 were subjected to the test procedure described above.The results are listed in Table 1.

WO 2019/185468 PCT/EP2019/057205 Table 1 No. 1.x Strukture Test Results 1 1,8-Bis(2-pyridyl)-3,6-dithiaoctane + 2 1,9-Bis-(3-pyridyl)-2,5,8-trithianonane + 3 1,13-Bis(2-pyridyl)-2,5,9,12-tetrathiatridecane + 4 (2R,3R)-1,4-bis[2-(2-pyridyl)ethylsulfanyl]butane-2,3-diol / (2S,3S)- 1,4-bis[2-(2-pyridyl)-ethylsulfanyl]butane-2,3-diol + 1,6-Bis(2-methylpyridyl)-meso-dithioerythritol 0 6 1,11-Bis(2-pyridyl)-6-oxa-3,9-dithiaundecane + 7 1,8-Bis(4-pyridyl)-3,6-dithiaoctane + 8 1,14-Bis(2-pyridyl)- 6,9-dioxa-3,12-dithiatetradecane + 9 1,15-Bis(4-pyridyl)-3,6,10,13-tetrathiapentadecane + (2R,3S)-1,4-bis[2-(4-pyridyl)ethylsulfanyl]butane-2,3-diol + 11 1-[2-[2-(2-imidazol-1-ylethylsulfanyl)ethylsulfanyl]ethyl]imidazole + 12 1 -methyl-2-[2-[2-[2-(1 -methylpyridin-1 -ium-2- yl)ethylsulfanyl]ethylsulfanyl]ethyl] pyridin-1-ium;methyl sulfate 13 1,13-Bis(3-pyridyl)-2,5,9,12-tetrathiatridecane + 14 1,13-Bis(4-pyridyl)-2,5,9,12-tetrathiatridecane + 1-[3-[2-[2-(3-imidazol-1-ylpropylsulfanyl)ethylsulfanyl]ethylsulfanyl]- propyl]imidazole + 16 (2S,3R)-1,4-bis(3-imidazol-1 -ylpropylsulfanyl)butane-2,3-diol + 17 (2R,3S)-1,4-bis(2-morpholinoethylsulfanyl)butane-2,3-diol 0 18 (2R,3S)-1,4-bis(2-imidazol-1 -ylethylsulfanyl)butane-2,3-diol + 19 1-[2-[(2R,3S)-2,3-dihydroxy-4-[2-(2-oxopyrrolidin-1-yl)ethylsulfanyl]butyl]sulfanylethyl]pyrrolidin-2-one + 2,2-bis[3-[2-(2-pyridyl)ethylsulfanyl]propoxymethyl]butan-1-ol + WO 2019/185468 PCT/EP2019/057205 1-[2-[2-[2-(2-imidazol-1- ylethylsulfanyl)ethylsulfanyl]ethylsulfanyl]ethyl]imidazole + 22 1,10-Bis(2-pyridyl)-3,8-dithiadecane + 23 (2R,3S)-1,4-bis(2-pyrazin-2-ylethylsulfanyl)butane-2,3-diol 0 24 (2R,3S)-1,4-bis(2-thiazol-2-ylpropylsulfanyl)butane-2,3-diol + 3-[2-(2-pyridyl)ethyl]-5-[2-(2-pyridyl)ethylsulfanyl]-1,3,4-thiadiazole-2- thione + 26 2,3-bis[2-(2-pyridyl)ethylsulfanyl]propan-1-ol + 27 6,8-bis[2-(2-pyridyl)ethylsulfanyl]octanoic acid + 28 2-[2-[[5-[2-(2-pyridyl)ethylsulfanylmethyl]-1,4-dithian-2-yl]methylsulfanyl]ethyl]pyridine + 29 4,6-bis[2-(2-pyridyl)ethylsulfanyl]-1,3,5-triazin-2-amine + 3-[2-[2-[(2S,3R)-2,3-dihydroxy-4-[2-[1-(3-sulfonatopropyl)pyridine-1- ium-2-yl]ethylsulfanyl] butyl]sulfanylethyl]pyridine-1 -ium-1 -yljpropane- 1-sulfonate + 31 3-[2-[2-[2-[2-[1 -(3-Sulfonatopropyl)pyridine-1 -ium-2-yl]ethylsulfanyl]ethylsuIfanyl] ethyl]pyridine-1 -ium-1 -yl]propane-1 - sulfonate

Claims

1./ 0274733170- Claims: 1. An aqueous composition comprising (a) metal ions comprising tin ions and silver ions and (b) at least one complexing agent of formula C1, C2 or C3 R-X-S-X-[D-X-]nS-X-R (C1) R-X-S-X-D-[X-S-]nX-R (C2) R-X-S-X-[D-X-]nS-X-R (C3) wherein X, X are independently selected from a linear or branched C1-C12 alkanediyl, which may be unsubstituted or substituted by OH; X, X are independently selected from (a) X, which may be further substituted by -X--COOR , -X-SO2-O-R, a C2 to C6 polyoxyalkylene group of formula -(O-CH 2-CHR)z-OH, or a combination thereof, and (b) -X-NH-CO-X-CO-NH-X-; X, X are independently selected from a chemical bond and X; X, X are independently selected from X; X is a linear or branched C 1 to C10 alkyl; X is selected from X and a divalent 5 or 6 membered aromatic group; R, R are independently selected from a monovalent 5 or 6 membered aromatic N-heterocyclic group comprising one N atom or two N atoms which are separated by at least one C atom, and its derivatives received by N-alkylation with a C1-C6- alkyl group, which may be substituted by -COOR or -SO2-O-R, and which aromatic N-heterocyclic group may optionally further comprise, under the proviso that X is substituted by at least one OH, one S atom; R, R are independently selected from a monovalent 5 or 6 membered aliphatic N-heterocyclic group comprising one N atom and one O atom; D is independently selected from S, O and NR; D is (a) a divalent 5 or 6 membered aliphatic heterocyclic ring system comprising 1 or 2 S atoms, or (b) a 5 or 6 membered aromatic heterocyclic ring system comprising at least two N atoms and optionally one or two S atoms; D is independently selected from S and NR; 277590/ 0274733170- n is an integer of from 0 to 5; z is an integer from 1 to 50; R is selected from H and a linear or branched C1-C12 alkyl; and R is selected from H and a linear or branched C1 to C6 alkyl; and R is selected from R and a cation.

2. The aqueous composition according to claim 1, wherein X and X are linear or branched C1-C8 alkanediyl, preferably C1-C6 alkanediyl, most preferably C1-C4 alkanediyl, which may either be unsubstituted or substituted by OH.

3. The aqueous composition according to claim 1 or 2, wherein the complexing agent is a compound of formula C1 or C2, wherein R and R are independently selected from N-imidazole, N-pyrazol, 2-thiazole, 2-pyridine, 3-pyridine, 4-pyridine, and 2-pyrazine.

4. The aqueous composition according to any one of the preceding claims, wherein the complexing agent is a compound of formula C3, wherein R, Rare independently selected N-pyrrolidone and N-morpholine.

5. The aqueous composition according to any one of the preceding claims, wherein n is 0 or an integer from 1 to 3, preferably 0, 1 or 2.

6. The aqueous composition according to anyone of claims 1, 2, 3, or 5, wherein the complexing agent is a compound of formula C1, wherein D is selected from S and O.

7. The aqueous composition according to any one of claims 1, 2, 3, or 5, wherein the complexing agent is a compound of formula C2, wherein D is selected from (i) a 5-membered aliphatic heterocyclic ring system having 2 S atoms or 1 S and one N atom, particularly dithiolane and thiazolidine or (ii) a 6-membered aliphatic heterocyclic ring system having 2 S atoms or 1 S and one N atom, particularly dithiane and thiomorpholine.

8. The aqueous composition according to any one of the preceding claims, wherein the complexing agent is a compound of formula C3, wherein D is S.

9. The aqueous composition according to any one of claims 1, 2, 3, 5, or 6, wherein the complexing agent is a compound of formula C1, wherein X and X are independently selected from a linear or branched C1-C8 alkanediyl, preferably C1-C6 alkanediyl, most preferably C1-C4 alkanediyl, which may either be unsubstituted or substituted by OH, X--COOR, or -SO2-OR. 277590/ 0274733170-

10. The aqueous composition according to any one of claims 1, 2, 3, 5, 7, wherein the complexing agent is a compound of formula C2, wherein X and X are independently selected from a linear or branched C1-C8 alkanediyl, preferably C1-C6 alkanediyl, most preferably C1-C4 alkanediyl, which may either be unsubstituted or substituted by OH.

11. The aqueous composition according to any one of the preceding claims, wherein the complexing agent is a compound of formula C3, wherein X and X are independently selected from are independently selected from a linear or branched C 1-C8 alkanediyl, preferably C1-C6 alkanediyl, most preferably C1-C4 alkanediyl, which may either be unsubstituted or substituted by OH.

12. The aqueous composition according to any one of the preceding claims, which comprises essentially no grain refiner.

13. The aqueous composition according to any one of the preceding claims, which is essentially free of copper.

14. The aqueous composition according to any one of the preceding claims, wherein the metal ions consist of tin ions and silver ions.

15. An aqueous composition according to any one of the preceding claims for use in a process for depositing tin silver alloys on a substrate comprising features having an aperture size from 500 nm to 500 µm.

16. A process for electrodepositing tin or a tin silver alloy onto a substrate by a) contacting a composition according to anyone of claims 1 to 14 with the substrate, and b) applying a current to the substrate for a time sufficient to deposit a tin or tin alloy layer onto the substrate, wherein the substrate comprises features having an aperture size from 500 nm to 500 µm and the deposition is performed to fill these features.

17. The process according to claims 16, wherein the aperture size is from 1 µm to 200 µm.

18. A compound of formula C1, C2 or C3 R-X-S-X-[D-X-]nS-X-R (C1) 277590/ 0274733170- R-X-S-X-D-[X-S-]nX-R (C2) R-X-S-X-[D-X-]nS-X-R (C3) wherein X, X are independently selected from a linear or branched C1-C12 alkanediyl, which may be unsubstituted or substituted by OH; X, X are independently selected from (a) X, which may be further substituted by -X--COOR , -X-SO2-O-R, a C2 to C6 polyoxyalkylene group of formula -(O-CH 2-CHR)z-OH, or a combination thereof, and (b) -X-NH-CO-X-CO-NH-X-; X, X are independently selected from a chemical bond and X; X, X are independently selected from X; X is a linear or branched C 1 to C10 alkyl; X is selected from X and a divalent 5 or 6 membered aromatic group; R, R are independently selected from a monovalent 5 or 6 membered aromatic N-heterocyclic group comprising one N atom or two N atoms which are separated by at least one C atom, and its derivatives received by N-alkylation with a C1-C6- alkyl group, which may be substituted by --COOR or -SO2-O-R, and which aromatic N-heterocyclic group may optionally further comprise, under the proviso that X is substituted by at least one OH, one S atom; R, R are independently selected from a monovalent 5 or 6 membered aliphatic N-heterocyclic group comprising one N atom and one O atom; D is independently selected from S, O and NR; D is (a) a divalent 5 or 6 membered aliphatic heterocyclic ring system comprising or 2 S atoms, or (b) a 5 or 6 membered aromatic heterocyclic ring system comprising at least two N atoms and optionally one or two S atoms; D is independently selected from S and NR; n is an integer of from 0 to 5; z is an integer from 1 to 50; R is selected from H and a linear or branched C1-C12 alkyl; and R is selected from H and a linear or branched C1 to C6 alkyl; and R is selected from R and a cation; excluding 1,8-bis(2-pyridyl)-3,6-dithiaoctane; 1,9-bis-(2-pyridyl)-2,5,8-trithianonane; 1,11-bis(2-pyridyl)-3,6,9-trithiaundecane; 1,6-bis-(2-pyridyl)-2,5-dithiahexane; 1,13-bis(2-pyridyl)- 277590/ 0274733170- 2,5,9,12-tetrathiatridecane; 1,9-bis(2-pyridyl)- 5-oxa-2,8-dithianonane; 1,8-bis(4-pyridyl)-3,6-dithiaoctane; 1-[2-[2-(2-imidazol-1-ylethylsulfanyl)ethylsulfanyl]ethyl]imidazole; 1-[2-[2-[2-(2-imidazol-1-ylethylsulfanyl)ethylsulfanyl]ethylsulfanyl]ethyl]imidazole; 1,9-bis(2-pyridyl)-3,7-dithianonane; 1,10-bis(2-pyridyl)-3,8-dithiadecane.

19. A compound according to claim 18 selected from: (a) if n=0, X is substituted by at least one, preferably two OH; and (b) if n is 1, D is O or NR and, if X and X are methanediyl, at least one of R and R is not 2-pyridiyl; and (c) if n is greater than 1, D is O or NR.

20. A compound according to claim 19 selected from: 1,9-Bis-(3-pyridyl)-2,5,8-trithianonane; 1,15-Bis(2-pyridyl)-3,6,10,13-tetrathiapentadecane; (2R,3R)-1,4-bis[2-(2-pyridyl)ethyl-sulfanyl]butane-2,3-diol; (2S,3S)-1,4-bis[2-(2-pyridyl)-ethylsulfanyl]butane-2,3-diol; (2R,3S)-1,4-bis[2-(2-pyridyl)ethylsulfanyl]butane-2,3-diol; 1,6-Bis(2-methylpyridyl)-DL-dithiothreitol; 1,6-Bis(2-methylpyridyl)-meso-dithioerythritol; 1,11-Bis(2-pyridyl)-6-oxa-3,9-dithiaundecane; 1,14-Bis(2-pyridyl)- 6,9-dioxa-3,12-dithiatetradecane; 1,11-Bis(4-pyridyl)-6-oxa-3, 9-dithia-undecane; 1,14-Bis(4-pyridyl)- 6,9-dioxa-3,12-dithiatetradecane; 1,11-Bis(4-pyridyl)-3,6,9-trithiaundecane; 1,15-Bis(4-pyridyl)-3,6,10,13-tetrathiapentadecane; (2R,3S)-1,4-bis[2-(4-pyridyl)ethylsulfanyl]butane-2,3-diol; 1-methyl-2-[2-[2-[2-(1-methylpyridin-1-ium-2-yl)- ethylsulfanyl]ethylsulfanyl]ethyl]pyridin-1-ium methylsulfate; 1,13-Bis(3-pyridyl)-2,5,9,12-tetrathiatridecane; 1,9-Bis-(4-pyridyl)-2,5,8-trithianonane; 1,13-Bis(4-pyridyl)-2,5,9,12-tetrathiatridecane, 1-[3-[2-[2-(3-imidazol-1-ylpropylsulfanyl)ethylsulfanyl]ethylsulfanyl]-propyl]imidazole; 1,9-Bis(4-pyridyl)- 5-oxa-2,8-dithianonane; (2S,3R)-1,4-bis(3-imidazol-1-ylpropylsulfanyl)butane-2,3-diol, (2R,3S)-1,4-bis(2-morpholinoethylsulfanyl)butane-2,3-diol; 4-[2-[2-[2-(4-pyridylmethylsulfanyl)ethoxy]ethoxy]ethylsulfanylmethyl]pyridine; (2R,3S)-1,4-bis(2-imidazol-1-ylethylsulfanyl)butane-2,3-diol; 1-[2-[(2R,3S)-2,3-dihydroxy-4-[2-(2-oxopyrrolidin-1-yl)ethylsulfanyl]butyl]sulfanylethyl]-pyrrolidin-2-one; 2,2-bis[3-[2-(2-pyridyl)ethylsulfanyl]propoxymethyl]butan-1-ol; 1-[2-[2-[2-[2-(2-oxopyrrolidin-1-yl)ethylsulfanyl]ethylsulfanyl]ethylsulfanyl]ethyl]pyrrolidin-2-one; (2R,3S)-1,4-bis(2-pyrazin- 2-ylethylsulfanyl)butane-2,3-diol; (2S,3S)-1,4-bis[2-(4-pyridyl)ethylsulfanyl]butane-2,3-diol; (2R,3R)-1,4-bis[2-(4-pyridyl)ethylsulfanyl]butane-2,3-diol; 3-[2-(2-pyridyl)ethyl]-5-[2-(2-pyridyl)ethylsulfanyl]-1,3,4-thiadiazole-2-thione; 2,3-bis[2-(2-pyridyl)ethylsulfanyl]propan-1-ol; 6,8-bis[2-(2-pyridyl)ethylsulfanyl]octanoic acid; 2-[2-[[5-[2-(2-pyridyl)ethylsulfanylmethyl]-1,4-dithian-2-yl]methylsulfanyl]ethyl]pyridine; 4,6-bis[2-(2-pyridyl)ethylsulfanyl]-1,3,5-triazin- 2-amine; (2R,3S)-1,4-bis(2-thiazol-2-ylpropylsulfanyl)butane-2,3-diol; 3-[2-[2-[(2S,3R)-2,3-dihydroxy-4-[2-[1-(3-sulfonatopropyl)pyridine-1-ium-2-yl]ethylsulfanyl] butyl]sulfanylethyl]-pyridine-1-ium-1-yl]propane-1-sulfonate; 3-[2-[2-[2-[2-[1-(3-Sulfonatopropyl)pyridine-1-ium- 277590/ 0274733170- 2-yl]ethylsulfanyl]ethylsulfanyl]ethyl]pyridine-1-ium-1-yl]propane-1-sulfonate; 1,3-Bis[3-[2-(2-pyridyl)ethylsulfanyl]propoxy]propane-2-ol; N1,N3-bis[2-[2-(2-Pyridyl)ethyl-sulfanyl]ethyl]benzene-1,3-dicarboxamide; 2,3-Bis[2-(2-pyridyl)ethylsulfanyl]propane-1-sulfonate; 2-[2-[5-[2-(2-Pyridyl)ethylsulfanyl]pentylsulfanyl]ethyl]pyridine; and their salts.